Instructions from the PI

This is a set of instructions for NOT monitoring programme P58-505 (PI: Håkon Dahle), scheduled for service observations. The purpose is to monitor a unique gravitationally lensed quasar with six images separated by up to 15'', discovered at NOT (Dahle et al. 2013, ApJ, 773, 146) and recently observed with HST and Chandra. The observations have a dual purpose: Firstly, we aim to make the first reverberation mapping measurement of the mass of a supermassive black hole at z~3. Secondly, we aim to make the first gravitational lensing time delay measurement involving de-magnified central images, constraining the central dark matter distribution of the galaxy cluster lens.

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.

The coordinates of the target are:
RA (J2000) = 22:22:08.6
DEC(J2000) = +27:45:35.6

We ask for the following observations with ALFOSC, 1h 25 min:

- HeI 588_6 (filter #45): 3 x 600 s
- SDSS i' (filter #111): 3 x 300 s
- SDSS g' (filter #120): 3 x 600 s

  see the nominal constraints and the table below for details

You can use the following dither commands:

alfosc.dither 3X 5 600      

alfosc.dither 3X 5 300      

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For calibration we request:

- 10 bias frames

- A set of three twilight flats for each band
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Nominal constraint set (moon and airmass constraints are implicitly set by the :
-Moon below horizon.
-Airmass < 1.5
-Seeing < 1.3''
-Thin clouds OK

The P60 plan for programme 58-505 would be as follows:

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