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New IR Standards for PANIC

 We have begun a program to define a new set of faint secondary IR standard stars for PANIC. New standards are needed because most existing standard stars, such as those described in Persson et al. (1998), are too bright for accurate photometric calibration with PANIC on the Magellan telescopes. These new standards will be chosen to be approximately 14th to 15th magnitude. We will greatly appreciate any observations by observers with the WIRC instrument on the du Pont telescope that can help to identify these stars. Below are instructions on how to obtain observations that will be helpful to identify these new standard stars. Preliminary magnitude information for the new standards will also be posted here.

 

Instructions for WIRC Observers:


Motivation:

 

The Persson et al. IR standards (AJ 116, 2475, 1998) are too bright to be observed with PANIC on Magellan, particularly if the seeing is better than 0.6", which is probably often going to be the case.

 

The faintest existing standards are ~ 12th at Ks; extending this to 15 - 15.5 will be sufficient. Some of the fields around the existing standards contain a large number of faint stars, some of which can be established as secondary standards.

 

The idea for this program then, is to use WIRC measurements of the existing standard star fields to make pictures somewhat deeper than required for a 12th magnitude standard, and to reduce the data as for "objects". Because the Persson et al. standard will be on one of the chips, there are no airmass or nightly transmission data to worry about, it is all relative photometry.

 

The final result will be a number of faint standards that have been checked in detail for variability and that have colors not too dissimilar from the Persson et al. standards.

 

The Standard Star Fields

 

The standards that have plenty of closeby field stars are in the following table. Please concentrate on these when you are doing standards:

 

New PANIC IR Standard Fields
Standard HST RA DEC Ks Exptimes
          Y J H Ks
9121 S255-S 6:42 -45 11.4   7 7 7
9129 S209-D 8:01 -50 10.5   4 4 4
9132 S312-T 8:25 -40 11.6   7 7 7
9136 S165-E 8:54 -54 12.1   10 10 10
9140 S262-E 9:45 -45 11.0   5 5 5
9144 S264-D 10:47 -44 11.3   7 7 7
9146 S217-D 12:01 -50 10.9   5 5 5
9147 S064-F 12:03 -69 11.7   7 7 7
9157 S273-E 14:56 -44 10.8   5 5 5
9172 S279-F 17:48 -45 12.0   10 10 10
9178 S808-C 19:01 -04 10.6   4 4 4
9183 P576-F 20:52 +06 11.9   10 10 10
 

 

If you could do any one of these standards as described below (next section) once every two nights of your run, that would be excellent. If you want to do more, even better. The seeing does not have to be pristine, nor do the photometric conditions. As the data start to accumulate, this web page will indicate which stars need more attention.

 

If you are doing a few standards per night, but only in one filter and only on one chip, it would help if you would still do the ones in the table.

 

Observing Procedures

 

Please use chip 2, as the NE quadrant of chip 1 is flakey. Place the standard a few arcseconds SW of center. Save data from all 4 chips: we might as well have it.

 

 

Loop = 3 for all

 

Exposure time = normal for the star; the table above gives suggested values. Assume for now that the Y exptimes are the same as for the other filters.

 

Dither pattern = "Square nine" or "dither nine" : this will take extra time but it will give better data and will be easier to reduce.

 

Dither offset = 11 arcsec is good.

 

Filters = J, H, and Ks, and Y if it is available.

 

Flats: Please get flats for all 3 (or 4) filters.

 

 

Reductions

 

SEP will reduce all the data. When you have your data on disk, we will need:

 
    • either the 'irx' raw frames plus your flats, OR the 'idf' frames,

       

    • the 'mask' frames that you make, if possible,

       

    • a copy of your logsheets.
 

If you do not plan to reduce your data right away, please lend us your raw tapes and logsheets for a few days.

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