QC PLOTS
	CURRENT	HISTORY
dark level
hot pixel
background rate
ron
QC1 database (advanced users): browse | plot
Click on CURRENT to see the current trending (Health Check).    Click on HISTORY to see the historical evolution of the trending.

The IFS-arm NIR detector is operated in cube mode (NDIT=NAXIS3) and nondestructive readmode (DET.READ.CURNAME=Nondest). All NDIT subintegrations are resolved as NDIT=NAXIS3 planes in a cube with 2048x2048 pixel (times NDIT planes). Detector characteristics are monitored via two raw types: DARK and BACKGROUND calibrations. Only BACKGROUND frames are used to calibrate science data. DARKs are acquired for monitoring the instrumental health.

IFS raw dark frame with DIT=30 sec (any plane of ther cube).

IFS Dark frames are taken daily with the same setups as the IRDIS detector dark calibrations:

• DIT=2sec, NDIT=40
• DIT=8sec, NDIT=25
• DIT=30sec, NDIT=15

In addition dark frames are acquired with the DIT and NDIT of the science observations.

The darks come as a single frames with one cube (NAXIS=3, NAXIS3=NDIT).

QC1 parameters

Trending

Dark level and the number of hot pixel is monitored for the three mentioned daily acquired health check setups.

History

• 2015-04-01 Dark frames, not all, but those that are acquired directly after a IFS flat exposure suffer from a persistence. See the problems page for more details. The issue was solved on 2017-05-01. There is a zoomed-in trending plot showing the dark-level and the RMS values to demonstrate (and not measure) the impact of the persistence.
• Since begin of operations on 2015-04-01, the background pipeline product suffers from an insufficient handling of the region in the lower left part of the detector with a high density of hot pixel.

	IFS raw background frame with DIT=30 sec and YJ-bands (INS4.OPTI13.NAME = DIC_K, INS2.MODE = IFS-H). (image with cuts = 200,300 ADU)
	IFS raw background frame with DIT=30 sec and YJH-band (INS4.OPTI13.NAME = DIC_H, INS2.MODE = NIROBS).

 

IFS background calibration frames are acquired with the DIT and NDIT of the dark frames. No prism is in the optical for background frames, however the background has a very small dependency on the CPI dichroic INS4.OPTI13.NAME=DIC_H or DIC_K. The pipeline does not (yet) subtract the dark of the same DIT.

From the technical point of view the difference between an IFS dark frame and an IFS background frame is, that in dark the key INS.COMB.ICOR = N_NS_OPAQUE, which means that all three coronograhic elements are OPEN and the OCS1.INS.OPTI1.NAME = CLOSED, while in a background frame INS.COMB.ICOR = N_NS_CLEAR, which means that again all three coronopgraphic elements are OPEN and the INS.COMB.ICOR = OPEN as well.

QC1 parameters

Trending

The instrumental background depends on the dichroic in the common path interface (CPI).
INS4.OPTI3.NAME=DIC_K means the YJH-bands are switched to IFS (and IRDIS receives the K-band alone).
INS4.OPI13.NAME=DIC_H means the YJ-bands are switched to IFS and H and K is switched to IRDIS.