Troubleshooting guide

estimated location of the box along the bottom of each cut, along with a horizontal threshold level through the
cut, and a vertical line indicating the estimated location of the peak of the alignment target; the first time
through there likely will be no targets in the boxes, and the line will be centered on a noise peak.
You can adjust the position of this vertical line, say if xbox detects the wrong peak, once the alignment targets
are in their boxes by moving the cursor to the correct location and hitting the f key. Hit q after looking at the fits
for every box, and the final graphical presentation of the estimated adjustments. Afterwards, xbox will print out
a lengthy set of values used for computing the offsets. The final bit of this indicates how much to move the
telescope and MOS wheel. Here is example output from xbox for a plate with ROT_PA = 90 (and rot_4m =
-90):
====================================================
*** MOVE TELESCOPE/ROTATOR by the following offsets:
Offset PA by -0.06 (0.01) degree
Offsets: -4.38" (1.09) 30.60" (0.21)
====================================================
The above translational offsets are printed in the order (δRA, δDec); also shown are estimated errors.
Translational offsets smaller than 0.5 pixel = 0.16" may be ignored; rotational offsets down to 0.01 degree
probably should be done.
Here is a step-by-step procedure for aligning the MOS plate:
1. Set instrument PA before acquiring target.
• This must be done first, as the telescope must be at zenith in order to move the rotator.
• For safety reasons, the telescope operator must make the rotation from the Cassegrain Cage.
• Run config.mos.dither.kp4m.pl, and set the parameter ROT_PA to the new value. Now the WCS
compass arrows will display correctly in ds9.
2. Verify that the xbox parameter rot_4m is correctly set for the PA.
3. Have telescope operator verify pointing on the North Port TV Camera.
• Use an SAO star or a Fixed Bright Star near to the target field.
• There should be a grease pencil mark on the TV monitor indicating where to zero the telescope
pointing.
• Take a quick image (2-5 seconds) on FLAMINGOS, and make certain the SAO star is well centered
on the array. If is not, center the star with relative.offset.kpno.pl, then take another image. Once it is
well centered, Z the telescope (cf. § III. B. Nightly Startup Tasks: Startup on the Sky).
• If the target field is too faint, or does not have any stars, consider adjusting focus on this pointing
check field (cf. 5 & 6, below).
4. Load the mask design image and region file into buffer 3 of ds9 or onto the observer's laptop.
• The images are usually kept in /data/4mguest/Maskfiles/.
• Flip and rotate until the image WCS matches that of a raw FLAMINGOS frame.
• Turn on tiling, with a vertical orientation; tiling of buffers 1, 2, and 3 is useful. Hide buffer 4.
5. Acquire target on FLAMINGOS in H or JH filter.
• Set exposure time to pick out alignment targets. Try an exposure time of 10 – 30 seconds if they are
bright, but do not let them saturate. You may need to use much longer integration times (60 – 120
seconds) if they are very faint.
• Attempt to visually pick out the alignment targets (stars or galaxies).
• If necessary, adjust telescope pointing with relative.offset.pl until the targets are within the central
region of the array.
FLAMINGOS@4-m, Ver. 2.39, 2013 April 23 Page 28 of 47