CLIMB Noise Tests 2010JUN - Revision history

Monnier at 20:03, 11 June 2010

2010-06-11T20:03:18Z

← Older revision		Revision as of 20:03, 11 June 2010
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	[[Image:~~Example~~.jpg]]		[[Image:Climb_Beam3only.jpg]]

	Fig 1.i have included a picture of the beams on the NIRO Target -- this one is Beam 3 only. You can see some issues with the centering.		Fig 1.i have included a picture of the beams on the NIRO Target -- this one is Beam 3 only. You can see some issues with the centering.

	[[Image:~~Example~~.jpg]]		[[Image:Climb_background.jpg]]
	Fig 2. Here is also a picture of the last step of NIRO align which seems to show that the background on the camera chip is abit off-center [not sure if this normal]. This suggests that the climb pixels on the left are being somewhat vignetted getting into camera.		Fig 2. Here is also a picture of the last step of NIRO align which seems to show that the background on the camera chip is abit off-center [not sure if this normal]. This suggests that the climb pixels on the left are being somewhat vignetted getting into camera.

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	I checked others files and there are strong sinusoids in most readout modes, but worst in the SYNC modes. One can see these strong spikes on the power spectrum window and our analysis confirms that these spikes are dominating the readnoise and should be addressed ASAP. Given that the sinusoids are not present at this strong level in NORM mode suggests that this spikes are caused by readout timing issues and not due to electrical interference. Rafael is quite keen to come up and help debug this and to experiment with some timing patterns.		I checked others files and there are strong sinusoids in most readout modes, but worst in the SYNC modes. One can see these strong spikes on the power spectrum window and our analysis confirms that these spikes are dominating the readnoise and should be addressed ASAP. Given that the sinusoids are not present at this strong level in NORM mode suggests that this spikes are caused by readout timing issues and not due to electrical interference. Rafael is quite keen to come up and help debug this and to experiment with some timing patterns.

	[[Image:~~Example~~.jpg]]		[[Image:camtest2010Jun.jpg]]

Monnier at 20:01, 11 June 2010

2010-06-11T20:01:36Z

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-Conclusions:
+We noticed that the camera performance as setup for CLIMB is significantly worse than for CLASSIC.  I will summarize our findings briefly below.   Unfortunately, the current conclusion is that CLIMB has 50% throughput (although I would wait to be sure of this until we get better seeing with CLIMB) and 3x the noise of CLASSIC (mostly caused by large amplitude sinewaves in the readout) -- However, we are confident this can be dramatically improved with some additional attention to alignment and the readout since CLASSIC uses the same camera optics and camera detector.    Lots to do this summer!!
-. CLIMB has 50% less throughput than NIRO.  One can see the Telescope -> Pixel Map does not follow the expected flux distribution, strongly suggesting there is some misalignment presently.
+. THROUGHPUT
-. NORM mode is worse than SYNC mode.  compare also 250Hz to 500Hz NORM.
+We compared camera counts for the same star from 2009 June CLASSIC with 2010 June CLIMB and found
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+[[Image:Example.jpg]]
-Details

192.153.157.221: New page: on UT 2010Jun10, we took some test data on a K=XX mag source using 500Hz SYNC and 500Hz NORM on CLIMB to compare the noise properties. We also put in the H-band filter to help estimate ...

2010-06-11T00:25:35Z

New page: on UT 2010Jun10, we took some test data on a K=XX mag source using 500Hz SYNC and 500Hz NORM on CLIMB to compare the noise properties. We also put in the H-band filter to help estimate ...

New page

on UT 2010Jun10, we took some test data on a K=XX mag source using 500Hz SYNC and 500Hz NORM on CLIMB to compare the noise properties. We also put in the H-band filter to help estimate the observed K band background counts. Lastly, we compared this to the NIRO performance, both noise and throughput from 2009 June.

Conclusions:

1. CLIMB has 50% less throughput than NIRO. One can see the Telescope -> Pixel Map does not follow the expected flux distribution, strongly suggesting there is some misalignment presently.

2. NORM mode is worse than SYNC mode. compare also 250Hz to 500Hz NORM.

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Details