NOTCam observing - step by step

This step-by-step guide is intended to guide you through the actual steps you have to take while observing and the commands you have to give on the data acquisition computer and the TCS, as well as the order of which to do things for typical observations. We refer to the more extensive NOTCam User's Guide as a preparatory reading and for further details. For spectroscopy we refer to the NOTCam spectroscopy web page for details. Since early 2008 we are using the SEQUENCER data acquisition system. See a list of NOTCam sequencer commands and NOTCam Sequencer Scripts.

Preparations beforehand

1. prepared your scripts beforehand preferrably using the script generator, which also gives you an estimate of the overheads. (The script generator lets you upload your scripts to the data acquisition computer in a directory coded by your proposal number.) You may also use available NOTCam scripts (see NOTCam Sequencer Scripts).
   
   
2. submitted a source catalogue via the web. If you don't have too many sources, you may also enter source coordinates directly into the TCS while observing, or alternatively typing tcs.enter-object <my-object-name hh mm ss.s dd mm ss.s epoch pm-ra pm-dec mag> in the sequencer command window.
   
   
3. prepared and submitted the target pointing scripts via the web. These scripts are particularly useful and time-saving if you do larger than 15'' dither steps, which is always the case for spectroscopy and beam-switching, and/or you wish to have the target oriented differently than the default for NOTCam. In principle, you don't need to submit a source catalogue if you make pointing scripts for all your sources.
   
   

Start up software

1. On the Lisa terminal login to marissa. Username is obs and password is obtained from staff.
   
   
2. Open two terminal windows. Start up the NOTCam Sequencer by typing in one of the windows: startobssys notcam. (The other window is intended for shutting down the system properly, which is done by typing the command: shutdownobssys notcam.)
   
   
3. A window pops up asking for the TCS access code. Find the code on the TCS by typing sh 1 for show page 1, and the access code number is shown on the top of the page. Type it in. All the NOTCam software windows will now be displayed.
   
   
4. The instrument status is shown at the top of the screen. If the status buttons are red and status is "Not initialized" you have to click on the Initialize menu and thereafter on the Init all movements button. Now status should be "Initialized". Then move all wheels manually by clicking on the UIF menus and buttons (see typical setups in tables below.) Status buttons should now turn green.
   
   
5. Commands are given in one of the 3 Sequencer Terminals . The default directory is /home/softremote/obs/ and you should type cd scripts/prop-ID/ where prop-ID refers to your proposal ID. Here you should find your previously uploaded scripts and finding charts. You can always add an extra Sequencer Window with the command: seqterm but for most applications 3 is enough: one to run imexam, another to run your observing script, and a third for any other need such as toggling sky-subtraction ON and OFF while observing.
   
   
6. The sub-program BIAS (Brorfelde Image Acquisition System) runs the detector and pops up 3 windows: one DS9 for real-time display of incoming images (the left one of the two DS9s), one array status window, and one window logging all status messages. The right-most DS9 display is the display for postprocessing and image examination. It is controlled from the sequencer windows. (If it does not behave well, kill it using the command notcam.killpostprocess and then restart it with notcam.setdisplay and then notcam.display-start). It is recommended to customize the DS9 setting zoom to "fit" and scale to "zscale".
   • To examine the image type notcam.imexam (works as in IRAF, quit with q). For more commands related to display and postprocessing see NOTCam Postprocessing control scripts.
   • Postprocessing results, such as FWHM seeing and background values are overlaid on the image if you set notcam.overlay yes. Note that the background level is as displayed(!) , i.e. sky-subtracted if you display with notcam.setskysub different from no.
   • You may select to have a simple sky-subtraction done automatically in the DS9 display with the command notcam.setskysub where the choices are either:
     • no for no subtraction, which is default at startup,
     • N to use the N'th last image, where N = 1 is the previous image, useful for most night-time applications, or
     • NC****.fits (the full name of a specified image to use).
   
   
7. Data files will be saved in:

   /data/notcam/

   a directory which is also cross mounted on the computer Florence on your right hand side, where you can do quick-look data reductions by starting up an IRAF session and enter the notcam package. Never delete any taken images!
   
   
8. The InfoSys monitor (above you to the right) displays the automatic NOTCam observing log, listing FITS headers for incoming files, as well as the System Talker, listing messages, warnings and errors from the Sequencer.
   
   
9. If you want to interrupt a script, then type Ctrl-C in the NOTCam Sequencer Window. This will stop the script, but not the on-going exposure (NB!), so you will have to wait for it to finish. The reason for this is that we do not have a working "abort" command for the NOTCam array. If the whole data acquisition program crashes, then first shutdown and then restart again with the commands:
   
   
   • shutdownobssys notcam
   • startobssys notcam

Afternoon preparations

1. Take a few test images with the command notcam.dark 0 to make sure the array reads out OK. If the camera has been idle for a while, the first image will contain accumulated charge. It is advisable to run a couple of notcam.clear commands. For example, the small script notcam.clean3 makes 3 clear commands plus a notcam.dark 0. Examples of how darks of 0 and 42 seconds integration time look like can be found on the page NOTCam calibration images.
   
   
2. Never delete images that have been taken! In principle, it is possible to avoid storing images by setting notcam.autosave_off, but we strongly recommend storing all images. There is no disk space issue. Therefore automatic data saving should always be on, and is set by typing notcam.autosave_on.
   
   
3. If you want to take darks, then use notcam.mdark t N if you take exposures with the exp, mexp mode, and notcam.dframe t N if you observe with the frame mode. We refer to The NOTCam User's Guide for a comment on the NOTCam darks. By using differential flats and sky-subtraction, the dark is automatically subtracted out, and you should not need to take darks for broad-band imaging. For spectroscopy it is recommended to take darks with the same exposure time and readout mode as your observations.
   
   
4. In order to setup the instrument for imaging you can run the sequencer script notcam.setup-ima cam filter-id, where cam is the camera of your choice (WF or HR), and filter-id is the Filter ID number . (The most used filters are J = 201, H = 203, and Ks = 207. All available filters, names and ID number are listed on the command window if your type the script name without input parameters.) All setups may be done manually by clicking on the desired items. NB! Note that notcam.setup-ima changes the focus-delta value according to filter and camera, while if you change the setup manually, you also have to change the focus-delta value manually! Check the tables below for typical setups.
   
   
5. For spectroscopy you can switch between the different wavelength regions (J, H, and K) with corresponding internal focus offsets by running the script: notcam.setup-spec. Note that the setup script does not change the position of the slit or the grism! This is more flexible for manual slit acquisition. Note also that K (208) rather than Ks (207) is used in order to cover 0.08 microns further towards the red, i.e. until about 2.36 microns.
   
   

   How to set up NOTCam for imaging. Use the default NOTCam telescope focus as a reference position (but check this every night). The focus-delta offsets are done automatically with reference to the default (i.e. the one for imaging in WF-cam and Ks).

   	Wide Field camera 0.234"/pix	High Resolution camera 0.078"/pix
   Aperture Wheel	# 4: OPEN Large	# 8: HR imaging
   Filter Wheel 1	OPEN, filter or polaroid	OPEN, filter or polaroid
   Filter Wheel 2	OPEN or filter	OPEN or filter
   Stop Wheel	# 12: 15mm ring	# 12: 15mm ring
   Grism Wheel	# 2: OPEN	# 2: OPEN
   Lens Wheel	# 1: WF Camera	# 3: HR Camera
   Camera focus	5650	20
   Telescope focus	Default: 23450 (check!)	Default: 23450 (check!)

   
   
   

   Example of NOTCam WF-cam spectroscopy setup. NB! Use the default telescope focus for NOTCam, since the focus-offsets are applied automatically in the script notcam.setup-spec.

   	Wide Field camera K-band	Wide Field camera H-band	Wide Field camera J-band	Wide Field camera Y-band
   Aperture Wheel	128 mu slit or OPEN large	128 mu slit or OPEN large	128 mu slit or OPEN large	128 mu slit or OPEN large
   Filter Wheel 1	OPEN	OPEN	OPEN	OPEN
   Filter Wheel 2	Ks or K	H	J	Y
   Stop Wheel	# 12: 15mm ring	# 12: 15mm ring	# 12: 15mm ring	# 12: 15mm ring
   Grism Wheel	OPEN or Grism#1	OPEN or Grism#1	OPEN or Grism#1	OPEN or Grism#1
   Lens Wheel	WF Camera	WF Camera	WF Camera	WF Camera
   Camera focus	4150	4350	4650	5750
   Telescope focus	Default: 23450	Default: 23450	Default: 23450	Default: 23450

   
   
   
6. For spectroscopy determine two good X positions on the array where you want to put your targets for the ABBA mode. We have used x=390 for position A, but the cold pixels may change with time. Check the latest bad pixel mask in the archive (i.e. cold pixel mask) or take your own flatfield to check (for instance 10 seconds in the K band will give enough counts to see the flat field with no lamps on). Make sure that several full columns around your positions X should be free of bad pixels, and keep in mind that position B (about 20''-60'' shifted to the right) should also be good. From the two good positions, you get as position A your input X value to be used in the slit-acquisition script notcam.slitoff X Y. The dither step size (in arc seconds) to use in the dither script notcam.abba t N object step is (B-A)*pixel-scale (0.234'' per pixel for WF-cam and 0.078'' per pixel for HR-cam).
   
   

Calibrations for spectroscopy

1. Set up the instrument according to your wishes. As an example we here wish to use the WF camera, the 128 micron slit (sid = 128) and Grism#1 (gid = 1) in the K-band regions (fid=208):
   notcam.setup-spec wf 208 128 1
   NB! This script does not move the slit and grism wheel. Make sure you put in the grism and the slit manually!
   
   
2. Use the calibration script notcam.calibexp to take your lamp spectra, let's say 5 halogen spectra with 7 sec exptime, 3 argon spectra with 10 sec epxtime and 1 xenon spectrum with 20 sec exptime: notcam.calibexp -n 5 -lmc halogen 7
   notcam.calibexp -n 3 -lmc argon 10
   notcam.calibexp -lmc xenon 20
   
   The -lmc stands for "leave mirror closed" and refers to the mirror covers. Note that the argon lamp may take some time to come on (up to 1 minute), and your first image may be dark, although a "sleep 20" is included in the script after issuing the lamp on.
   
   
3. If you wish to take lamps for another spectroscopy setup, then start from point 1. again

Domeflats for imaging

1. Reset the TCS safety system (two buttons and two keys next door).
   
   
2. Power-on the telescope by typing power-on on the TCS terminal (you have to confirm with a 'y'). Wait until the Top Unit power shows ON on the TCS status page 1.
   
   
3. Set the telescope to an altitude of 45 degrees by typing alt 45 on the TCS terminal. Open mirror covers by typing o-m-c.
   
   
4. Switch on the NOTCam QC lamp on the panel on the wall in front of you (turn switch rightwards to the "on" marker). The lamp intensity can be adjusted on the upper panel with the large knob that goes from 0 to 100. Default value is around 56, useful for the broad band filters used with the WF camera.
   
   
5. Select camera and filter using the script notcam.setup-ima.
   
   
6. The default intensity of 56 for the lamp is useful for the broad-band filters and the WF camera. Typical exposure times are then 5-7 sec for the K bands, and around 10-15 sec for the J and H bands. For all narrowband filters used with the WF camera, the lamp intensity should be set to 100 (maximum). The exposure times needed vary considerably, from 10 sec for filter #223 and #224 (the CH4 s and l filters) to 40 sec or more for the rest. If you use narrowband filters with the HR camera you will need very long exposure times and skyflats before sunset are recommended.
   
   
7. Take a set of 8-10 exposures with the lamp ON and another set with the lamp OFF, for instance by using the multi-exposure command mexp t N. For the differential approach to work, the exposure time must be the same for the ON and OFF images.
   
   
8. Turn off the lamp, put the telescope to zenith (on the TCS type zenith, and close the mirror covers (on the TCS type: c-m-c). You don't have to turn off power to the telescope if you are going to start observe within the next hour.

Start-up 20 min before sunset for skyflats

1. If you want to take differential sky flats (recommended), then be ready to start at this point about 20 minutes before sunset, in order not to miss the useful window during evening twilight. The exact timing of this window depends on the sky quality (dust, temperature) and the altitude of your blank field. Only a few minutes too late, and you may get too low S/N or a useless flat-field sequence.
   
   
2. If the telescope power is not yet on, check that the TCS safety system has been reset (or reset it), and then type power-on on the TCS terminal. (Wait until the Top Unit power shows ON on the TCS status page 1 before presetting to a target.)
   
   
3. In the SEQUENCER terminal type tcs.setup-tel-notcam. This script sets some default parameters for observing with NOTCam, such as field orientation, default focus for WF+Ks imaging, and allowed guide probe areas.
   
   
4. If you want twilight skyflats, then load the blank-field-and-focus-star catalog on the TCS with the command read blanks and find a useful blank field target in the eastern sky that is not too low (i.e. RA 1-4 hours more than current ST). Preset to it 15-20 minutes before sunset. Select the target in the TCS catalogue and press numerical key 4 to preset. Or type in the sequencer window goto-object my-object where my-object is the name of the blank field as given in the TCS catalogue ''blanks''.

5. Open the telescope hatches from the TCS terminal, starting with the upper hatch: open-upper-hatch (o-u-h). While upper hatch is opening you have time to open the three sideports that are not facing the sun, if weather permits. When upper hatch is open, do open-mirror-cover (o-m-c) . If weather allows, you can also open-lower-hatch (o-l-h).
   
   

   Example of skyflat sequence for JHKs and both cameras. This must be repeated when the sky has become dark to get the faint images.

   Camera + filter	Sequencer cmd: notcam.	Typical exptime (t)
   HR + Ks	setup-ima hr 207	10
   HR + H	setup-ima hr 203	5
   HR + J	setup-ima hr 201	5
   WF + Ks	setup-ima wf 207	10
   WF + H	setup-ima wf 203	7
   WF + J	setup-ima wf 201	15

   
   
   
   Examples of recent (Sep-09) raw skyflat images for the HR-camera (left) and the WF-camera (right). The structure is similar for all filters. Note that this particular blank field (Blank4) is full of stars in the near-IR.
   
   
   

6. Select camera and filter-id using the notcam.setup-ima script.
   
   
7. If you need both cameras and all JHKs filters, then follow the sequence in the above table, and start with the Ks filter. The suitable exptimes vary with season, dust, temperature and altitude of the blank field. Take short test exposures as the sky brightness decreases . (If you saturate, run notcam.clean3). When you have approximately 25000 ADU in an exp t integration (where 3 < t < 20), then immediately start to take skyflats typing:
   
   notcam.skyflat t
   
   The script takes 8 individual flats and dithers 10'' between exposures, and needs about 3-4 minutes to run. Change filter and restart the script. Cycle filters in the order KsHJ-KsHJ or KsZHJY -KsZHJY. NB! It is important to always use the same exposure time for the same filter and camera setup in the bright and faint pairs, otherwise the differential method will break down.
   
   The typical exptimes given in the table above is an example where the observing sequence started 11 minutes before sunset, the pointing was ESE and the zenith distance 48 degrees. The sky intensity varies with pointing, sky quality and time of year. It is possible to take both cameras (HR and WF) in JHKs and that takes about 50 minutes in total. If you want to have all the 5 broad-band filters ZYJHKs, then you can fit in only one camera for each twilight. NB! Repeat exactly the same sequence in order to get the faint images.
   
   
8. When finished with skyflats, you can open the remaining sideport.
   
   
9. If you did not get skyflats, you can check the down-loadable NOTCam flat field archive.
   
   

Autoguiding

1. Switch on the guide TV camera with the command tcs.tv-on (or only tv-on on the TCS) when it is dark outside. Switch on the autoguider monitors (above you).
   
   
2. If you use Targe Pointing Scripts, then the correct guide area has already been defined in the script and you don't need to consult the section Using the correct NOTCam guide area below.
   
   
3. The default autoguiding mode is currently the automatic mode which is set by the command tcs.auto-positioning-full. In this mode the star box is centred on the screen, the best guide star is automatically entered, and the autoguiding is started. This also corrects the pointing. The only thing you need to do, is to verify that the TCS says "guiding" and that the guide star is in focus.
   
   
4. If you want optimal guiding, adjust the focus of the TV camera until the star is round and sharp. On the TCS you can enter values by typing e.g. tv-foc 460. The default mode is currently automatic-TV-focus which adjusts the TV focus automatically for telescope focus changes. The TV focus will be set to default value for NOTCam upon every preset. This may not be perfect, however. If you wish, undo it by typing manual-TV-focus. You may also change the star box size with the TCS command star-box-quadrant-size or s-b-q-s to smaller than default if you have good seeing, and oppositely for bad seeing.
   
   
5. If you are not using target pointing scripts, then before pointing to another target you have to stop autoguiding with the command ag-off.
   
   

If you for some reason want manual autoguiding, on the TCS type auto-pos-off. You can move the autoguider star box to the guide star with the TCS cursor keys [Alt Function] + [Arrow Key] after having scrolled the Change Move mod (5) key until the mode is "Star box". Then type ag-on to start autoguiding. Stop autoguiding with ag-off. Check the Observers Cookbook for more autoguiding recipes.

Problem shooting:

1. If you see guide stars on the screen but autoguiding is not started, then use the command auto-pos-retry.
   
   
2. You may wish to change the tv-filter to open, tv-fil o, or to any other option (b = blue, g = grey, r = red, y = yellow).
   
   
3. If there are no guide stars on the screen, even after setting tv-fil o, it could be due to an error in the catalog, then try the second best guide star by issuing the command tcs.get-guide-star 2 (using the default area) or tcs.get-guide-star 2 NOTCam-Re (using the reduced area). This is also an option if you do not like the default guide star found automatically, for instance because it turns out to be double. See also NOT web tool for guide stars .
   
   
4. If your dither steps (teloffsets) are larger than allowed for a given guide area (see subsection below), then this may eventually lead the guide probe to move outside the permitted area. If this happens, the notcam.teloffset command stops the guide probe and switches off the autoguiding, while the dither step will be performed and your dither script will continue. If this happens, you will notice that the guide star is no longer in the autoguider star box, and you should restart guiding manually by moving the star box(NB!) onto the star and start relaxed! autoguiding using the ag-rel command on the TCS. You can avoid all this by selecting the correct guide area before starting your dither script. See below. Our recommendation is to prepare target pointing scripts in advance.

NOTCam Focusing for imaging mode (focus-pyramid)

1. Set up NOTCam for focusing with notcam.setup-focpyr cam where cam is your camera selection (WF or HR).
2. Make sure you have set tcs.auto-positioning-full or on the TCS simply: auto-pos-full
3. Go to a focus field, e.g. a focus star in the "blanks" catalogue, and wait until it is autoguiding.
4. Take an exposure, such as notcam.expose 15
5. Use this image for further sky subtraction, i.e. setskysub <image-name>
6. Move around 15'' in any direction: notcam.teloffset -15 5
7. Take a new exposure notcam.expose 15
8. Use notcam.focuspyr or notcam.focuspyr-auto to determine the best focus offset from the current focus position. You must add this number to the current focus value to get the new focus value. Change the telescope focus: tcs.focus-position <new-focus-value> and iterate at least once.
9. Remember to take out the Focus Pyramid when finished. Or simply run the setup script notcam.setup-ima cam filter-id, where cam is wf or hr, and filter-ID is 201(J), 203(H) or 207(Ks) or any other filter you want.

NOTCam Imaging

1. Make sure you are in your home directory in the Sequencer Terminal. This is /home/softremote/obs/scripts/proposal-ID/, where proposal-ID is the sub-directory with your proposal ID number. This is where your submitted scripts have been uploaded.
   
   
2. Point the telescope to your target by running the pointing script you made through the web interface Pointing Script Generator.
   Alternatively, go to your target manually in either of the two ways:
   
   • Select the target in the TCS catalogue and press numerical key 4 to point the telescope.
   • Type in the sequencer window guide-object my-object where my-object is the name of the target as written in the TCS catalogue.
   
   
   
3. Setup the instrument with the camera and filter of your choice using the script notcam.setup-ima.
   
   
4. Observe your targets using your own previously made observing scripts, or our set of NOTCam template dither scripts. Useful examples are listed (see link above for details):
   
   
   • notcam.9point frame 6 8 my-object 10 2 3
     This does a 9point dither (3x3 grid) and at each position takes an exposure using the exposure command frame 6 8 (which gives a 48s exptime). The dither step size is 10'' and a skew of 2'' is applied to tilt the grid. The dither is run 3 times. Recommended for deep imaging where it is vital that the sky can be well calibrated.
     
     
   • notcam.5point exp 6 1 my-object 15 3 1
     This does a 5point (dice) dither, and at each position takes an exposure using the exposure command exp 6 (note that you need to add N=1 as input). The dither step size is 15'' and a skew of 3'' is applied to tilt the grid. The dither is not repeated. Useful for bright targets where you don't worry so much about the sky.
     
     
   • notcam.beamswitch frame 10 10 my-object S-posX 240 10 2
     This is a beamswitch mode going alternatingly ON and OFF target. At each position the exposure mode frame 10 10 (giving an exptime of 100s) is used. The OFF field is in the direction S-posX at the distance 240'' from the ON field. Both the ON and the OFF fields are being dithered by 10'' step sizes in a 3x3 grid fashion, using a skew of 2'' to tilt the grids. Useful for extended targets.
     
     
   • notcam.loop-frame 3.6 3
     Staring mode observing, using the exposure mode frame 3.6 3 (giving an exptime of 10.8s). The script is repeatedly taking exposures until interrrupted with Ctrl-C. The same type of loop script exists for the exposure mode exp t.
   
   
   NB! If you use the Script Generator to make your own scripts, then remember to give in the proposal-ID and upload them. Run your script my.script by simply typing ./my.script. NB! It has to be made executable first (chmod ugo+x my.script). If you want to modify an existing NOTCam script, you can copy the original to your own directory and edit it.

   cp ~staff/notcam.as05-jhk my.as05-jhk

5. You can load a NIR standard star catalogue on the TCS by typing read JHKstd_leggett.cat or read JHKstd_hunt.cat. Reference papers: Leggett et al. 2006, MNRAS 373, 781-792 and Hunt et al. 1998, AJ 115, 2594. Or you may use our Selected JHKs standard fields for NOTCam and load them on the TCS by typing read notcamstd.cat. For these last sources there are sequencer scripts that make the full JHKs cycle (see NOTCam Sequencer Scripts).
   
   
6. An IRAF package called notcam.cl is available for Quick Look reductions while observing. It is run off-line on the "Florence" computer where the data disk is cross-mounted. Check the Data reduction section in the NOTCam User's Guide for instructions.
   
   
7. If the seeing improves, or if you decide to change from the WF-camera to the HR-camera, it is always recommended to redo the focusing sequence for the camera you are using.
   
   
8. Below is shown the orientation of the sky on the array with different values of the field rotation. The default field rotation with NOTCam is -90 (defined as the best orientation to minimize LN2 spilling). In order to manually set the field orientation use the TCS command field-r xxx.
   
   If you want a given position angle (PA) on the sky, you have to calculate new_field = -180 + PA, where PA is measured from North and eastwards. Also, if you wish to modify your field rotation, then calculate new_field = current_field + angle, where angle (in degrees) is positive for clockwise rotation and negative for counter-clockwise rotation, referring here to the direction you rotate your stars on the array. Your current field-r is always given on the TCS status. You don't have to worry about this if you use the pointing script generator to prepare your observations.
   
   
   
   
9. Be aware that working at zenith distances larger than 60 degrees may cause some spilling of LN2, and subsequently cause a slight temperature increase of the detector. For a typical night the detector temperature has been found to change by +-0.1 degrees only.
   
   
10. NB! In order to have a stabilized detector where all effects subtract out well, it is recommended to take an exposure equal in time and readout mode to the one you use in your scripts before starting the script, i.e. take the target acquisition image the same way you would observe. At every change of integration time and/or filter the background level changes and the array needs to stabilize again. Alternatively, you can just skip the first image during data reductions.
    
    For this same reason, it is not recommended to use the clear command in the beginning of each script if you plan to repeat the same script in order to get deep images. The clear command is useful if you have saturated, however, and want to get rid of memory effects.
    
    

NOTCam Focusing for spectroscopic mode

It may vary slightly, and this value is typically determined using the Focus Pyramid in the beginning of each night (see above section on NOTCam focusing for imaging mode). The default telescope focus for spectroscopic mode is about 200 units lower WF-cam spectroscopy and about 150 units higher for HR-cam spectroscopy, but NB! these offsets are accounted for automatically when using the script notcam.setup-spec.

If you wish to check the focus manually while observing in spectroscopy mode, you may use your target if 1) it is stellar, 2) fainter than 11th mag, and 3) at a high altitude, or select a focus star or a focus field.

1. Select your spectroscopy mode (slit, grism, camera, filter) and run the script notcam.setup-spec with these entries. Note that neither the slit, nor the grism, has been moved. If they were already in, then take them out of the beam manually by clicking on the UIF menu.
2. Make sure you have set tcs.auto-positioning-full or on the TCS simply: auto-pos-full
3. Point to the focus field (i.e. focus stars in the "blanks" catalogue) and wait until autoguiding is OK.
4. Take a short exposure typing notcam.expose t where t is 10-15 sec.
5. Dither one step to use the first image for sky subtraction: notcam.teloffset 10 10
6. Set the first image as sky-subtraction image setskysub NC****.fits
7. Take another exposure with the same exposure time
8. Check the stellar profile, its FWHM and roundness using the imexam tool
9. If you doubt your star is in focus, or you wish to check other focus values, then:
   • modify the telescope focus manually by typing tcs.focus-position new_value, where new_value is the current value you read off from the TCS display plus or minus some smaller offset
   • rerun notcam.setup-spec (important to get the offset right, since adjusint the main telescope focus value resets all offsets to zero)
   • take a new exposure with the same exposure time

NOTCam Spectroscopy

1. If you have not already done so, setup NOTCam for the spectroscopy mode you will use, i.e. your choice of lens/filter/slit combination, either manually by clicking on the UIF, or using the script: notcam.setup-spec (type the script name without input parameters and the available options will be listed).
   
   
2. It is recommended to always use autoguiding. Automatic acquisition of guide star and starting of autoguiding is done if you have set the command tcs.auto-positioning-full. Note, however, that for most spectroscopic observations with NOTCam, the dither along the slit is typically larger than 15'' and you should therefore not rely on the default guide area, but rather select a special guide area. This is easily solved by preparing in advance your Target Pointing Scripts. If not, you have to do as follows when you have pointed to your target:
   
   
   • stop autoguiding: tcs.ag-off
   • select another guide area, for instance the reduced area which guarantees autoguiding for dither step sizes of 60'': tcs.get-guide-star 1 NOTCAM-reduced
   • restart autoguiding: tcs.auto-positioning-retry
   
   If your dither step along the slit is larger than 60'', you have to specify an even smaller guide area, for instance NOTCAM-S-posX, since for typical ABBA scripts the dither is towards positive X. For more details on guide areas see the section on Autoguiding above.
   
   
3. The default field rotation for NOTCam is field-r -90, but for your spectroscopic observations you may want another field angle, either because you want two targets in the slit, or because you wish to observe your target on the parallactic angle. This is most easily done by preparing your Target Pointing Scripts, which we recommend. Otherwise, you have to follow the descriptions below:
   
   
   • In the first case you can either determine beforehand the position angle of the slit on the sky (P.A. measured from North and Eastwards). Then on the TCS give the new field-r value as (-90 + P.A.). Point to your target using the normal "Preset" button which is function key 4 in the Catalogue (CAT) menu. Alternatively, you can use the script notcam.slitrot when pointing at your target. It allows you to select your two targets interactively inside the imexam environment and gives as output the new field-rotation angle you have to use.
     
     
   • In the latter case, when you point the telescope to your target, use the "Preset w par ang" which is function 6 in the Catalogue (CAT) menu. When comparing with your finding chart note that your field will be rotated differently for each target. On the DS9 you can click on the Zoom menu and the button Align to get your field aligned with North Up and East Left. For the "Preset w par ang" to work correctly, i.e. to orient the slit vertically with respect to the horizon, the instrument-parallactic-angle 0 must be defined in the TCS. This is the default when the telescope is setup for NOTCam with the tcs.setup-tel-notcamcommand.
   
   
4. Both the field-rotation as well as the guide-area setting can be well planned in advance and entered into the NOTCam target pointing scripts .
   
   
5. For each new target it is recommended to take a short image (2-5 sec) of the slit to measure the Y-value at the X position you defined as a good in the afternoon (see above.) Start notcam.imexam and measure the Y-position using the key 'k' in the DS9 display. These XY values must be noted down to be used in the SEQUENCER command notcam.slitoff. Then take out the slit.
   
   
6. Take an acquisition image of the field with the broad-band filter you are going to use for your spectroscopy. Run the command notcam.slitoff X Y, and locate your target on the DS9 and put the cursor on it followed by typing
   • 'a' for gaussian centering or
   • 'x' for using this exact pixel value,
   and then type 'q'. Now the telescope moves and the guideprobe follows. Iterate at least once!
   
   Comment: If your target is brighter than the sky, then you may use the slit image as a "sky-subtraction" image (setskysub imagename.fits ), and you will automatically see where your target lands on the negative slit image. If your target is fainter than the sky, you will have to take two aquisition images as a start, with a teloffset in between, such that you can use the first one as the sky-sbutraction image.
   
   
7. When you are satisfied (one iteration is usually enough), put in the grism and the slit. Start the dither script. The ABBA dither mode is frequently used, and you may use the available dither script in the following way: notcam.abba t N object step, for example notcam.abba 10 10 HIP2435 25, where the input parameters t and N refer to the notcam.frames t N command. The parameter step is the telescope offset from position A to B along the slit, in arc seconds. Position A is the starting position.
   
   
8. Calibration lamps:
   
   It is highly recommended to take arc lamps while pointing at your target, due to flexure of the instrument (see the spectroscopy commissioning report for details). Do not move the slit or the grism before taking the lamp images. Typical NOTCam spectroscopy calibration exposure times.
   
   Use the notcam.calibexp script to take the number of lamps you wish. The script will stop autoguiding, turn off TV, close mirror covers, switch lamp on, take exposure, switch lamp off, and depending on your choice either 1) leave mirror covers closed (if you set -lmc), or 2) re-open, switch on TV, set back the correct TV-filter, and re-acquire autoguiding.
   
   
9. Here is an example of a typical sequence of calibration commands starting out with K-band spectroscopy using the WF-camera and the 128 micron slit:
   
   
   • notcam.calibexp -lmc halogen 7
     Takes one halogen lamp image of 7 seconds exptime, leaving the mirrors closed.
   • notcam.calibexp -n 2 -lmc argon 10
     Takes two argon lamp images of 10 seconds exptime, leaving the mirrors closed. NB! The argon lamp may be a bit slow in coming on.
   • notcam.setup-spec wf 203 128 1
     Now we wish to take the same lamp sequence for the H-band region. The slit and the grism have not been moved.
   • notcam.calibexp -lmc halogen 7
     Takes a halogen lamp image of 7 seconds, leaving the mirrors closed.
   • notcam.calibexp -n 2 argon 2
     Takes two argon lamp exposures of 2 seconds, and re-opens the mirror covers when finished, leaving you ready to continue observing your target. Note that if the upper hatch is not open, the mirror covers will not open even if you ask it. If the mirror covers are not open, the TV will not be switched on.
   
   
   Alternatively, all steps done by notcam.calibexp can be made manually:
   1. Stop autoguiding by typing tcs.ag-off.
   2. Close mirror covers by typing tcs.close-mirror-covers or on the TCS terminal simply: c-m-c. This command also switches the sensitive guide TV off!
   3. When the mirror cover is closed, turn on the lamp of your choice (1 = halogen, 2 = argon, 3 = xenon) with the sequencer command e.g. tcs.baffle-lamp-1-on. NB! Note that the argon lamp may take up to a minute to come on, while the others should be immediate.
   4. Take the lamp calibration images using notcam.expose t where the typical exposure time t for various setups can be found in the table Typical NOTCam spectroscopy calibration exposure times.
   5. If you need the same lamp for several wavelength regions (J,H,K), then change the instrument setup using the script notcam.setup-spec without touching the slit and the grism.
   6. Remember to turn off the lamp typing e.g. tcs.baffle-lamp-1-off.
   7. Possibly you want another lamp, as well. When finished, make sure all the lamps are off! You can check the commanded status of the lamps on the TCS status page 30.
   8. If all lamps are off, then open mirror covers to proceed observing: tcs.open-mirror-covers (you have to verify this with a "y").
   9. When the mirror covers are open, then you can switch on the guide TV again with the command tcs.tv-on. You also have to set the TV-filter back to what it was, e.g. tcs.tv-filter Open.
   10. Restart guiding with the command tcs.auto-positioning-retry if you will continue observing the same target, or switch to the next target.
   
   
   
10. Acquire your next target, make sure you are autoguiding, take out the grism, and start again from step 5. above.
    
    

At the end of the night

1. When the background starts to become high in the morning twilight it is time to turn off the sensitive guide tv. On the TCS type tv-off. Turn also off the two autoguider monitors.
   
   
2. If you want to take twilight sky flats, find a blank field in the western sky which is not too low (RA a couple of hours less than ST). Preset to it about 40 minutes before sunrise. You might need to continue until after the sun is up if you do the HR-camera or narrow-band filters. Therefore: Close sideports first! If they are stuck, use the handle to lift them up on the rails again. Don't use violence.
   
   
3. Take test exposures and start the script notcam.skyflat t with t=3 for WF-Cam and YJHZKs filters about 40 minutes before sunrise. Do the filter cycle the oposite way now: YJHZKs-YJHZKs.
   
   
4. When finished with skyflats close mirror cover c-m-c, close lower hatch c-l-h and as soon as lower hatch is closed, close also upper hatch c-u-h. When upper hatch is closed, set telescope to zenith position by typing zenith on the TCS. Then park the building building by Start/Stop menu - 4. When the building has come to a complete stop, then turn off power to the telescope by typing power-off, and turn down the TCS screen brightness (do not switch off the monitor!).
   
   
5. If you start a script that takes a number of long darks before you leave, then inform about this in the EON report and indicate when it will be ready.
   
   
6. In the morning (or before starting the next night) you should shut down the Sequencer by typing in a terminal window: shutdownobssys notcam. NB! do not use the Sequencer Window!. Note that the Sequencer has to be restarted every afternoon to get the right TCS access code. Type in a terminal window: startobssys notcam.
   
   
7. Remember to complete the WWW report forms (Fault Report, EON, EOR) that are linked from the NOT homepage.
   
   
8. Lock the dome when you leave the telescope, and lock the service building before you go to sleep.
   
   

Trouble shooting

1. Problems like 1) condensation on the entrance window, 2) signs of dust specks on the optics, and 3) interference pattern due to pick-up noise, are described in the section "Encountered Problems" in the NOTCam User's Guide.
   
   
2. It is known that Ctrl-C in the Sequencer Window, although it is the only way to interrupt a script, often causes the Sequencer to crash completely. This is probably related to the known problem with the abort command for NOTCam. In this case you have to shutdown the NOTCam sequencer and restart it as follows:
   • shutdownobssys notcam
   • startobssys notcam

3. In all cases of doubt, contact staff.
   
   

Reminder of most used commands - Imaging

1. SEQUENCER: tcs.setup-tel-notcam
2. TCS: power-on
3. TCS: read blanks and select blank field in the east
4. TCS: preset with numerical key 4
5. TCS: o-u-h (open-upper-hatch)
6. TCS: o-m-c (open-mirror-cover)
7. TCS: o-l-h (open-lower-hatch)
8. SEQUENCER: notcam.setup-ima cam filter-id
9. SEQEUNCER: notcam.skyflats t
10. TCS: tv-on (when it is dark) + switch on AG monitors
11. TCS: preset with numerical key 4
12. SEQUENCER: notcam.setup-focpyr cam (then find focus)
13. TCS: foc-pos xxxxx (use foc-del xxx for filter offsets)
14. TCS: read catalogue/mycatalogue.cat (will be appended in buffer)
15. TCS: ag-off (stop autoguiding before going to next object)
16. TCS: preset with numerical key 4
17. TCS: If beam-switch mode: g-g-s 1 NOTCAM-Be_NS (for example)
18. TCS: auto-pos-retry
19. SEQUENCER: run your target acquisition script NC_IMA_myobject.script and it substitutes all previous points from 14.-18.
20. TCS: optimal guiding may need adjustment of TV-focus: tv-foc xxx
21. SEQUENCER: notcam.setup-ima cam filter-id
22. SEQUENCER: run your observing script my.script (possibly you need chmod ugo+x my.script)
23. TCS: tv-off (when it gets bright)
24. TCS: c-m-c (close-mirror-covers)
25. TCS: c-l-h (close-lower-hatch)
26. TCS: c-u-h (close-upper-hatch)
27. TCS: zenith (parks telescope)
28. TCS: Building-Park-Position (parks building)
29. TCS: power-off (when telescope and building have stopped moving)

Reminder of most used commands - Spectroscopy

1. SEQUENCER: tcs.setup-tel-notcam
2. TCS: power-on
3. TCS: read blanks and select blank field in the east
4. TCS: preset with numerical key 4
5. TCS: o-u-h (open-upper-hatch)
6. TCS: o-m-c (open-mirror-cover)
7. TCS: o-l-h (open-lower-hatch)
8. SEQUENCER: notcam.setup-spec wf 208 128 1 to setup for K-band spectroscopy with WF-cam
9. SEQEUNCER: notcam.skyflats t (if you want spectroscopic sky flats)
10. TCS: tv-on (when it is dark) + switch on AG monitors
11. TCS: foc-pos 23200 (default for spectroscopic mode is roughly 23450 - 200)
12. SEQUENCER: NC_SPEC_myobject.script to run your target acquisition script (recommended for spectrosocpy since you can specify parallactic angle and the reduced guide area)
13. SEQUENCER: put in slit, take an image exp 3, determine y-position
14. SEQUENCER: take out slit, take an acquisition image exp t
15. SEQUENCER: notcam.slitoff X Y, select target, iterate once
16. SEQUENCER: put in slit and grism, start script notcam.abba t N obj step
17. SEQUENCER: notcam.calibexp -n 2 -lmc halogen 7 to take two halogen flats and leave mirror closed
18. SEQUENCER: notcam.calibexp -n 2 argon 10 to take two argon arcs and re-open mirror covers
19. TCS: tv-off (when it gets bright)
20. TCS: c-m-c (close-mirror-covers)
21. TCS: c-l-h (close-lower-hatch)
22. TCS: c-u-h (close-upper-hatch)
23. TCS: zenith (parks telescope)
24. TCS: Building-Park-Position (parks building)
25. TCS: power-off (when telescope and building have stopped moving)
26. SEQUENCER: If you want darks, start your script mydarks.script