Instructions from the PI

This is a set of instructions for NOT monitoring programme P74-516 (PI:Håkon Dahle), scheduled for service observations. The purpose is to monitor three of the five currently known gravitationally lensed quasars where the lens is a galaxy cluster. The main purpose of the observations is to use the light curves to make time delay measurements between multiple lensed quasar images in order to estimate the value of the Hubble constant. We will also determine the level of microlensing in each lens system. The target information and the observing strategy are reported below.

Please let us know whether you carried out these observations.

Thank you!

Best regards,
Håkon Dahle

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For the "monitoring" observations use the script indicated by the OB.

Calibrations:

- A set of three twilight flats for the SDSS g' filter
- alfosc-calibs

Available scripts

For these observations use the appropriate script for the date, complie the OB if needed.

Observations

J0909+44, 50 minutes

J1004+4112 35 minutes

CJ1153+0756 50 minutes

J1326+48 13 minutes

J2222+2745 20 minutes

Program Tracking
Proposal	74-516
Semester	P74: 20261001 - 20270401
Principal Investigator	Haakon Dahle
Programme	A novel pathway to solving the Hubble tension.
Instrument	ALFOSC
Time Allocation	3.2 hours Monitoring; 17.6 hours Monitoring; 14.7 hours Monitoring; 7.1 hours Monitoring; 10.6 hours Monitoring
Total Nights	53.2h
Type	Monitoring
Notes	Fixed dates to be scheduled
Total Time Spent	01:02 (hh:mm)

Proposal	Date	Time	Type	Targets	Files	Comments	Status
74-516	2026-10-11	01:02	Monitoring	SDSSJ0909, DESIJ1011	ALJj110143 - ALJj110145,	Targets observed successfully with clear skies and sub-arcsec seeing.	Observed

Should any of the observations have been carried out using the OB system, you will find additional information HERE