UKIRT Infrared Deep Sky Survey Observer Notes

UKIRT Infrared Deep Sky Survey Observer Notes

These notes are intended solely for UKIDSS Observers coming to the telescope.


Procedures are more or less the same as for visiting observers on Cassegrain proposals and PATT. However, here we gather together the relevant links.

ArrivalYou should arrange to arrive at the JAC offices by mid-morning on the day before your first observing night. This gives your support astronomer time for a discussion of any issues you need to be aware of (instrument status, the various queues, etc.). The link to the left takes you to the JAC visitor information page.
ReservationsThe JAC reservation request form must be sent to JAC by each observer planning to attend the observing run. Please complete ALL sections – your arrival time in Hilo is important so that we can properly schedule your travel between JAC and the Mauna Kea Residence. If you encounter any problems with this form, please fax this text form. For Proposal Number, enter UKIDSS. For Principal Investigator, enter A Lawrence.
SafetyYou will be given a safety briefing by your support astronomer. In advance, please read the specific section of the JAC safety manual linked to the left. Your support astronomer will be your associated staff member.


These sections detail the summit operation of the surveys and assume that you have read the basic online documents (Operational model, execution tools documentation, OMP documentation).


Startup and shutdown of WFCAM are both described on the RUNUP page. You should be familiar with this before you get to the summit.

MSB Selection

In the QT, select Semester UKIDSS, Instrument WFCAM, set the seeing and sky brightness. Click Search and select MSBs from the top of the resulting queue. Make sure you read the observer notes in the MSB. All other execution is as stated in the UKIRT Preparation and Execution documents.

See the WHAT’S ON TONIGHT PAGE for priorities.


The TSS is responsible for ensuring that the nights’ data are entirely calibratable. This includes taking observations of dawn twilight flats on selected nights and dark frames at an appropriate frequency. These calibrations are mandatory, and the TSS will carry them out interspersed with the survey MSBs.

Survey Priorities

The UKIDSS surveys are set by the JAC and UKIDSS Survey heads. In all cases, the TAG priority (the integer part in the priority column) is initially 50. TAG adjustment may be used by the UKIRT survey support scientist to selectively enhance the completion of a survey found to be falling behind (this will be obvious in the integer part of the priority column entry). The decimal part is set by the internal priority per MSB, which is generally as set initially by the survey head, but maybe varied by JAC if particular MSBs are considered to be important to complete. Observers are asked not to ignore MSBs at the top of the queue if they are (for example) badly placed/setting; if this is the case, the priority may have been set high in order that the survey does not miss its chance at getting those particular MSBs. Note that instructions on the Tonight Page are more frequently updated and should be taken to override anything written here, in cases of a discrepancy.

Night logging

Please ensure that you make use of the following three levels of night logging:

  1. Shift Log Comments – These are displayed at the top of the OMP night log and should be used for “top-level” statements of progress – e.g. sky conditions, project switches, etc.
  2. Obs Log Comments – These are interspersed with frames in the detailed observation listing at the end of the log and should be used to comment on properties of individual frames (e.g. when flagging a frame as bad, please make a note of why it is).
  3. Accept/Reject – When you complete an MSB, a dialogue box pops up which asks you to accept or reject the data taken. It includes a text box; please use this to describe the result of running the MSB, even if it’s to say that there is no evidence of any problem.

Rejecting MSBs

It is not easy to give hard and fast rules on when a partially-completed MSB should be rejected or accepted, but some guidelines are given here, along with a statement of what happens to the data in such cases. Point by point:

  1. All data acquired at the summit are shipped to CASU, and WFAU, whether or not the MSB they came from, was rejected. 
  2. You can’t cause someone to miss out on data by rejecting an MSB; the worst that can happen is that the data are taken over again, which is an efficiency issue only.
  3. Accept/Reject status is obtained from the OMP database by CASU and appears in the FITS headers, which reach the science archive. So there is never ambiguity.
  4. If you are 50% of the way through an MSB and the weather conditions go off, reject it, and it will be repeated in its entirety on a subsequent night.
  5. A reasonable cutoff for not rejecting is 90% completion. In that case, please ensure that you put a note in the night log and use the observer feedback form for the project in question so that the survey head can reinstate whatever part of the MSB they wish.

Empty Queue Time

If there are no suitable UKIDSS MSBs given current conditions, then the UKIDSS observer should firstly exercise flexibility of 0.1 arcseconds in the entry in the “seeing” field in the QT. The rest of the fall back sequence is detailed on the Priorities Tonight page. If still nothing, then you are allowed to do your own backup if you have any, but it is essential that in doing so you adhere to the WFCAM template library sequences, which will ensure that the data will be reducible when they reach the CASU offices for pipeline processing. A project is available for this type of observing: U/UKIDSS/B2. If you have none of your own backup, check U/UKIDSS/B1 (the staff equivalent, which will occasionally have MSBs for execution).