P52-032: Monitoring the enigmatic binary V838 Mon

No weather or seeing restrictions.

Target: V838 Mon 07 04 04.85 -03 50 51.1 ep=2000

Standard star: HD 19445 or HD 84937 (TCS catalogue entry SP0305+261 and SP0946+139, respectively)

Observing setup: Run B (monitoring)

Instrument: ALFOSC

Total observing time: 5 min

Optical elements:

No weather or seeing restrictions.

Target: V838 Mon 07 04 04.85 -03 50 51.1 ep=2000

Observing setup: Run C (ToO)

Instrument: ALFOSC

Total observing time: 1h

Optical elements:

No weather or seeing restrictions.

Target: V838 Mon 07 04 04.85 -03 50 51.1 ep=2000

Standard star: HD 19445 or HD 84937 (TCS catalogue entry SP0305+261 and SP0946+139, respectively)

In the afternoon:

• See general instructions how to start the observing system.

• Go to the programme directory where all the scripts are located. In Sequencer window type cd /scripts/52-032/

• Insert the coordinates of the target into the TCS catalogue. In Sequencer window type catalogue

• Read in ALFOSC standard stars catalogue. In the TCS user-interface type read FS.cat

• Make 9 full frame biases and copy them to /data/service/calib/. Make sure you use the default 200Kpix/sec read out rate.
  In Sequencer window type:
  resetxy
  remsave_on
  rempath /data/service/calib
  readspeed 200
  resetxy
  mdark 0 9
  remsave_off

• Start the script to make windowed biases for spectroscopy (only for Run A and C). In Sequencer window type: spec_bias.script
  Takes 3 minutes. Script is making 7 biases windowed in x direction and 7 biases windowed in y direction.

In the twilight

In the night

Photometry: Run A, B and C

1. Point to the target. In Sequencer window type point_ima.script
   

2. Do imaging, filter by filter. To start the scripts type in Sequencer window:
   
   Run A and C (16 min) :
   i.script exposure_time
   R.script exposure_time
   V.script exposure_time
   B.script exposure_time
   U.script exposure_time
   
   Run B (5 min):
   B.script exposure_time
   R.script exposure_time
   
   where the script name is stating clearly what filter is going to be used and exposure_time is the exposure time in seconds for a given filter:

   Table for expected exposure times

   FILTER	Expt. [sec]
   i	0.5
   R	2
   V	10
   B	150
   U	500

   Each script is setting up the optical element, putting proper focus delta for a given filter and making one science frame. You only have to check if the peak counts of the target (pointed with an arrow on the finding chart) are equal or below the nonlinearity limit (see below for instructions). The source may vary unexpectedly therefore your interraction is highly NEEDED and APPRECIATED! If the target has peak counts more than 350 000 ADU, please run the script again with the reduced exposure time. Total observing time for each run is given above.

   
   

How to check the peak counts of the star?

If DS9 window has not been started earlier type display-start in Sequencer window. To load the last frame in the DS9 window type display. Then type imexam. Move the cursor on top of the target on the DS9 window and type r. This gives a radial profile plot of the target in additional window (irafterm). From there peak counts can be seen or read from the lower row as a fifth value.

Spectroscopy: Run A and C (40 minutes)

1. Spectrum with the grism #4. In Sequencer window type g4.script V838Mon 400
   where V838Mon is an object name and 400 is spectrum exposure time in seconds. Follow instructions given in the Sequencer window. Script will firstly point to the target with the parallactic angle. Secondly, script needs your help to place the object on the slit. See 7 arcminutes finding chart above and 3 arcminutes below. Note that the orientation of the acquisition images is according to parallactic angle. When the target is on the slit the script continues on its own until you hear astrowakeup. The script is setting up proper optical elements (grism #4, slit 1.0), acquiring proper window, making halogen lamp flat, HeNe arc and science frame. The script takes approximately 11 min.

2. Spectrum with the grism #17. In Sequencer window type g17.script V838Mon 500
   where V838Mon is an object name and 500 is spectrum exposure time in seconds. Follow instructions given in the Sequencer window. Script will firstly point to the target with the parallactic angle. Secondly, script needs your help to place the object on the slit. See 7 arcminutes finding chart above and 3 arcminutes below. Note that the orientation of the acquisition images is according to parallactic angle. When the target is on the slit the script continues on its own until you hear astrowakeup. The script is setting up proper optical elements (grism #17, slit Vert_0.5), acquiring proper window, making halogen lamp flat, ThAr arc and science frame. The script takes approximately 16 min.

   
   

3. If the night is photometric obtain spectra of standard star with both grisms. Choose one of the two spectroscopic standard stars (SP0305+261 or SP0946+139) which is at the similar airmass as the target was observed. Same scripts as for a target are used.

   In sequencer window type:
   g4.script SP0305+261 1
   g17.script SP0305+261 12
   or
   g4.script SP0946+139 1
   g17.script SP0946+139 12

   where 1 and 12 are exposure times, SP0305+261 and SP0946+139 object names. For both standards with grism #4 exposure time is 1 sec (total observing time approximately 4 minutes) and with grism #17 12 sec (total observing time approximately 8 minutes). NB! The pointing script expects that the ALFOSC standard stars catalogue (FS.cat) has been inserted into TCS catalogue. Spectra scripts need your help to place the object on the slit.

   Click here for finding charts of the standard stars.