Hubble Division/Mission Perspective HST Focus Status Distribution

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TO:

MEMORANDUM

DATE:

Distribution

September 19, 2002

SUBJECT: Questions and Answers from TIPS Meeting on 19 September 2002

Hubble Division/Mission Perspective

Presenter – Rodger Doxsey

No questions.

HST Focus Status

Presenter – John Krist

Q: When will the decision be made on a recommendation for a mirror move? If the new data do suggest the continuation of focus degradation, how long will it take to schedule the mirror move?

A: At this point it is highly probable that we will have a mirror move. The scheduling process will take a couple of weeks.

Q: Regarding the WFPC2 and ACS focuses, how can we tell that they are at the same focus? Is there any time dependency?

A: For the monitoring program, WFPC2 and ACS observations were taken simultaneously. At present, the assumption is that there is no time dependency, but we will continue to monitor the focus as part of an ongoing program.

Q: Would the mirror move affect NICMOS?

A: No. The 3  m mirror move will not be very significant for NICMOS since it operates at longer wavelengths.

Q: How many measurements using the HRC have been made?

A: 16 measurements per orbit per visit for the ACS/HRC. 12 measurements per orbit per visit for WFPC2.

Q: Do we understand the breathing?

A: The existing breathing model does not work with the current setup. We will need to update the breathing model to accommodate the present configuration.

ACS Status

Presenter – Jennifer Mack

Q: Did we inform the astronomical community regarding the recent updates to CALACS and PyDrizzle?

A: Announcements were made in the last STAN, and we have posted tables summarizing the changes on the ACS web page.

Q: How are the hot pixels defined for ACS?

A: A hot pixel is defined as having a dark count greater than 0.08 electrons/seconds for the HRC, and greater than 0.04 electrons/seconds for the WFC. The median dark current is 7 counts/hour.

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WFC3 Status

Presenter – Sylvia Baggett

Q: Do we have any information on the stability and the read noise level of the new IR detectors?

A: At this time we do not have any.

Q: Do we know for sure that the high dark current problems with the IR detectors are due to the machine used for the manufacturing process?

A: Rockwell traced the problem back to the machine. The manufacturing process was moved to a new facility, and the machine used was only at its first initial run. Data gathered seemed to indicate that the observed problem is consistent with the machine setup. Rockwell will go back to the old facility and use the old machine to manufacture the new detectors.

Q: When will WFC3 be shipping to GSFC?

A: The electronics are coming now, and the optical bench will ship by October 1 st .

COS Status

Presenter – Ken Sembach

Q: Do we expect the QE to be better with the spare detector?

A: Yes, we do expect the QE to be better due to the modification of the fabrication process.

Q: When will COS be going through testing against flight software?

A: The testing will go on in the fall, consisting of both timing tests and commanding tests.

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