Peaking Up

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Peaking Up

Up:CGS4 Handbook

CGS4 Peakup rows

The following are suggestions as to which rows to use for peaking up with CGS4. Be aware that the row number that the telescope system specialist will use is not the same as the row the data appear on in the data reduction.

256 x 178 array:

Peakup on row 140. This corresponds to row 96 in data reduction.

256 x 48 subarray:

Peakup on row 128: This corresponds to row 24 in data reduction.

256 x 32 subarray:

Peakup on row 128: This corresponds to row 18 in data reduction.

Limiting magnitudes for peakup

Peakup will only work for objects bright enough to be detectable on the array within a few seconds. For objects that are too faint for efficient peakup there are two methods you can use to position those objects on the CGS4 slit. i) Measure the offsets of your target from a nearby bright star; you will then be able to peakup on the bright star and slew to your target using the measured offsets. (Please use a recent image if possible to that proper motion is not a factor). ii) If your target is optically bright, it is possible to peakup on a nearby CMC star and accurately point to your target without the need for offsets.

The tables below are a guide on limiting magnitudes for peakup. Objects fainter than these limits are not bright enough for the peakup process to be carried out efficiently (although if you are prepared to sacrifice observing time in order to find a faint target in the slit, it is possible to peakup on fainter objects than these limits suggest - please contact Tom Kerr for more details). The limits assume excellent conditions at the summit.

40 l/mm grating

Waveband	Limiting Magnitude
J	15
H	14.5
K	14
L, L'	9
M	7

Echelle

Waveband	Limiting Magnitude
J	12
H	11.5
K	11
L, L'	7
M	5.5

Last Modification Date: 2000/01/04 - Last Modification Author: Tom Kerr
Tom Kerr (tkerr)

Contact: Tom Kerr. Updated: Wed Oct 6 11:58:10 HST 2004

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