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Frequently asked questions1. Preparation of the MSBs 2. Data handling 3. Guide stars 4. General 1. Preparation of the MSBs.Q. I have a few MSBs that are 1h 30m long. Is this okay? Q. I need to include J,H, and K sky observations. Can I use a survey container to do that? 1) J target, J sky, H target, H sky, K target, Ksky or... 2) J target, H target, K target, J sky, H sky, K sky ? A. It depends on the science. Closely alternating target and sky will give you finer calibration if you are really worried about sky levels, but will increase your overheads. Q. Is there a quick way in the OT to examine the coverage of the array in a survey container? Unfortunately, there's no elegant way to do this yet. The reason for this is that the instrument configuration is usually specified below the Survey Container folder row in the OT, so for each given position, the JSky plot window doesn't know which instrument configuration it should be overlaying. One possible workaround for this is if you were to temporarily copy the WFCAM component from inside your Survey Container folder block up to between the parent Site Quality component & parent Survey Container Folder, so that the Survey Container positions all then inherit the instrument setup. You should then be able to successfully plot out each of your Survey Container's fields in turn, overlay the science fields, & blink between them. Just remember to delete the temporarily inserted extra WFCAM component afterwards, once your positions are all set up, so as to avoid possible unforeseen (& unwanted) inheritances. The other possibility is that (for a 2x2 tile) you could just specify the tile central position, & use a combination of x-offsets & y-offsets of +/-395 arcseconds for each position. Q. Is it ok to overfill the database (going over the allocation) to increase chances of getting data in different sky conditions? A. Yes. It is actually a good strategy provided you don't use sky constraints that are more relaxed than the one specified in your proposal. If you overfill the database, please be very clear in specifying your priorities, especially toward the end of your allocation. Q. Can I relax the sky conditions constraints specified in the proposal? A. No, unless specifically authorized by UKIRT Associate Director and TAG. Q. Can I use the OT "skyflat" element to obtain a sky flat? A. Yes, you can use the skyflat element to obtain a sky flat. Note that this is not normally needed, since sky flats are routinely taken by the Observatory staff, and made available for data reduction. Q. If I decide to obtain a skyflat observations, do I need to set adequate constraints so that it is executed at the beginning of the night, when the sky is still bright? A. If your run is classically scheduled, you will be the one deciding when to run your MSBs, so you'll be able to run it at the beginning of the night. If your run is flexibly scheduled, then there is no real way to do this. Specifying a very narrow set of sky constraints in order to get high enough sky counts will probably just wipe out the possibilities of getting your MSB done. In any case, we do not see the need of taking your own set of skyflats. We do routinely take flats in every filter, and it is out experience that flat field variations are negligible compared to sky effects. Q. How much lead time would you recommend to prepare the MSBs. A. We do not enforce any hard deadline, but it is of course recommended to upload your MSBs as soon as possible. In practice, if you can upload a first attempt about 3/4 weeks before your run, that gives us enough time to vet and iterate with you on any fixes/improvements that might be implemented. Q. If I want to increase the total exposure time, is it more efficient to increase the number of coadds or do additional exposures/readouts? A. Increasing the number of coadds is the best way in terms of efficiency (smaller overheads) but it is not the recommended method. Rather, you should consider increasing the number of repeats. The reason for doing this are 2: 1) if you use multiple coadds and have one bad exposure for some reason, it will affect all the coadded exposures, and 2) you will have longer time between the individual raw frames being written, so you'll have less frequent visual feedback on the data acquisition while observing. Finally, if you combine a long sequence of coadds with a long sequence of jittering, you might end up not sampling the sky frequently enough. Q. How can I retrieve my OT program? A. Use the Fetch Program function within UKIRTOT software. It will ask you for your password. You can have a new password issued by visiting the OMP web pages. Q. My MSB validate ok, but when I try to validate the whole progam, I get many "SCHEMA VALIDATION" errors. A. Unfortunately, this is a known bug of the OT. Either validate your MSB individually, or ignore the Schema Validation errors. 2. Data handlingQ. What sort of data volume is to be expected per night? Q. Is there a way to bring home a copy of the raw data? Can I connect my external hard disk? How should it be formatted? Q. What is the reason we can't save the data to the drive immediately? 3. Guide stars
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| Chip | Xoffs | Yoffs |
| 1 | 795 | 795 |
| 2 | -795 | 795 |
| 3 | -795 | -795 |
| 4 | 795 | -795 |
Q. How many observers can we have at the summit?
A. There is enough room for at least 3 observers.