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IUE Project Electronic Newsletter

NASA-Goddard Space Flight Center (GSFC)

Vol. 5, No. 7 - July 1997


IUE Project is Going Out of Business

The IUE project will cease to exist after September 1997. Once the project terminates, there will be neither user support services (e.g., user accounts, web site information, Data Analysis Center (DAC) support, analysis software updates, etc.), nor additional data reprocessing. Until then, our highest priority is to finish the NEWSIPS processing of all NASA IUE images. However, if you have questions or special requests, now is the time to ask, and we will be as responsive as possible. The IUESIPS and NEWSIPS data are and will continue to be available from the National Space Science Data Center (NSSDC) at Goddard. The project will also deliver all documentation (much of which is only available in hard copy), and NEWSIPS and IUE DAC software, to NSSDC.

- Ron Oliversen


IUE Image Processing News

LWP High-Dispersion Processing Begins!

As of mid-June, we have been processing LWP high-dispersion images with NEWSIPS. You are welcome to send us your requests for priority processing through the request form at:

http://hypatia.gsfc.nasa.gov/IUE/search/IUE_usrreq.html

Status of NEWSIPS Processing

We are on track to finish the NEWSIPS processing of all NASA images by the end of September. Here is how each data set stands, as of July 17, 1997.
SWP low dispersion
Nearly all of the images have been processed (95%). A small number of the images obtained after 1993 are still in the processing queue for reprocessing to apply the updated sensitivity degradation correction. The remaining unprocessed images are either flat fields or problem images awaiting resolution.
LWP low dispersion
Nearly all of the images have been processed (94%). The remaining unprocessed images are either flat fields or problem images awaiting resolution.
LWR low dispersion
This data set is currently being processed. As of July 17, 69% of the images have been processed. Some of the images affected by the noise model error are still in the processing queue to be reprocessed.
SWP high dispersion
Nearly all of the images have been processed (95%). All of the images requiring reprocessing to apply the updated SWP sensitivity degradation correction have been reprocessed. The remaining images are either affected by DMU corruption (see below) or are problem images requiring resolution.
LWP high dispersion
This data set is currently being processed. As of July 17, 46% of the images have been processed.
LWR high dispersion
Processing of this data set is scheduled to start in mid-August, pending the availability of the final ripple and absolute calibrations from VILSPA.
We note that the SWR images, as well as the FES images, are not being reprocessed as NEWSIPS data. The original IUESIPS versions of these data will continue to be available, if anyone wishes to use them.

Flagging Those Pesky Images Affected By DMU Corruption

As you may know, towards the end of IUE operations, some of the science data were affected by corruption by the Data Multiplexer Unit (DMU). In an affected image, some of the raw pixels were set to 159 DN instead of the correct data value of 160 to 191. They can be identified on a statistical basis by performing a histogram of DN values and noting the overabundance of pixels with a value of 159 DN.

Our colleagues at VILSPA have screened all of the raw images taken since October 1994 in order to identify images affected by the DMU anomaly. Among the NASA images, 96 LWP and 423 SWP images were affected. We are currently implementing the NEWSIPS software to flag these images, and will begin processing them in the next week or so. (Note that some images have already been processed and archived but do not include the flagging - they will be reprocessed.)

In the NEWSIPS software, we have defined a new quality flag to indicate a pixel that may be affected by DMU corruption. In an image identified as corrupted by the screening process, each pixel with a value of 159 DN is flagged as "possibly corrupted". (Since the corruption can be identified only on a statistical basis, it isn't possible to say which of the pixels with 159 DN are valid and which have corrupted values.) The nu flag is set to -8 for any pixel with 159 DN. The nu flags are then carried along in the processing just as the other nu flags are handled. These images are identified in the COMMENTS and in the processing history. In the following example, 14 pixels were found to have values of 159 DN, of which 12 pixels are expected to be corrupted values. Please note that these pixels may or may not affect spectral data; some corrupted pixels may fall outside the region containing useful scientific data.

COMMENT BY RA:  EXP 1 APER L C=202,B=36
COMMENT BY RA:     0 MISSING MINOR FRAMES NOTED ON SCRIPT
COMMENT BY RA:     0 BAD SCAN STARTS NOTED ON SCRIPT
COMMENT BY RA:  EXP 1 TRACKED ON GYROS
COMMENT BY RA:  S   PREP USED
COMMENT BY RA:  OFFSET 1  FROM: SAO 119431
COMMENT BY RA:  OFFSET 1  COORDINATES: 12 27 37.1 +02 30 27
COMMENT BY RA:  OFFSET 1  MAGNITUDE: 9.300
COMMENT BY RA:  FESCOUNT 1 =   120     FES-MODE 1 = FO
COMMENT BY RA:  WARNING: Some LWP low dispersion spectra taken after 12 Nov 1992
COMMENT BY RA:  are contaminated by scattered solar spectrum.
COMMENT BY RA:  WARNING: Image affected by the 159 DN anomaly
COMMENT BY RA:     14 pixels with 159 DN, corrupted:    12 + 1 /-  3
HISTORY IUE-LOG STARTED                             04-JUL-1997 14:43:10
HISTORY PROCESSING SYSTEM: NEWSIPS VERSION 2.5.4
HISTORY ULTRIX VERSION
HISTORY LWP29832
HISTORY PROCESSED AT GODDARD SPACE FLIGHT CENTER
HISTORY ****************************************************************
HISTORY ****************************************************************
HISTORY START RAW_SCREEN                             4-JUL-1997 14:46:37
HISTORY    6 BRIGHT SPOTS DETECTED
HISTORY    0 MISSING MINOR FRAMES DETECTED
HISTORY *** WARNING: THIS IMAGE IDENTIFIED AS AFFECTED BY DMU CORRUPTION
HISTORY           ALL PIXELS WITH DN = 159 FLAGGED AS POSSIBLY ERRONEOUS
HISTORY LARGE APERTURE SPECTRUM WILL BE EXTRACTED AS
HISTORY           POINT SOURCE
HISTORY LARGE APERTURE CONTINUUM DN LEVEL = 180
HISTORY SMALL APERTURE CONTINUUM DN LEVEL =   0
HISTORY BACKGROUND DN LEVEL =  33
HISTORY END   RAW_SCREEN                             4-JUL-1997 14:47:58
HISTORY ****************************************************************

Questions?

If you have any questions about IUE processing or the Final Archive, please feel free to contact me any time at imhoff@iuegtc.gsfc.nasa.gov or 301-794-1470. Thanks!

- Cathy Imhoff


Recent Software and System Changes

10-Jun
A new version of prolog was implemented which corrects an error in displaying prolog information on Unix and PC platforms when the IDL procedure resides in the user's working directory.
18-Jun
OpenVMS version 7.1 was installed on IUE.
18-Jun
A corrected version of prolog was implemented which is compatible with IDL search paths using VMS logicals.
20-Jun
A new version of platform was implemented which points to the correct mail utility on systems running DEC Unix.
24-Jun
IDL version 4.0.1b was installed on IUE.
25-Jun
The IUE merged log was updated. VILSPA data up to June 17th are included.
27-Jun
A new version of idfile was implemented which fixes a bug which occurs when the full data path name contains the phrase .LAB. Also, a new version of idt was implemented which appends a 0 to image numbers less than 10,000 when creating file names (e.g., files will be named swp01234hlg.dat rather than swp1234hlg.dat).
- Randy Thompson

Macintosh Platform Software Updates

We recently found several programs in the Macintosh version of the IUEDAC software that are out-of-date when compared to those programs on the other supported platforms. These differences likely occurred at those times when the software was being updated on the other platforms, which are believed to be running current versions of all programs. These programs, available from our Beta software area at

http://iuewww.gsfc.nasa.gov/pub/software/beta/

are coadd.pro, datarec.pro, gotordaf.pro, iue3drd.pro, iueatrd.pro, iueim.pro, iueqictape.pro, lbl.pro, makemelo.pro, and vicar.pro. They should be included in the pro folder under the iuelib folder.

In addition, there are three routines that should not be included in the pro folder: iueqictap (not iueqictape.pro) is just an empty file; idb_item_info.pro is obsolete; and tvroam.pro only belongs in the VAX distribution. All of these changes will be incorporated in the next version of the IUEDAC software library, to be released in the next few months.

- James Caplinger


Possible Error in IUESIPS File Names

When IUESIPS files are requested from NDADS in RDAF format, the last 2 letters of the file name generally designate which aperture was used. For example, the file name SWP09744HLG indicates a (high dispersion) large aperture exposure, while SWP09744HSM indicates a small aperture exposure. The aperture is determined from information extracted from the header record of the original GO-format file. However, this information wasn't added to the file headers until October, 1980.

It appears that when the aperture information is not available, the NDADS software calculates RDAF-format file names assuming the large aperture was used. Users should therefore be cautioned that small aperture images processed before 1980 may be given file names indicating large aperture data. The problem is expected to be corrected in the near future.

If it is uncertain which aperture was used, users should first check the GO comments stored in the first 10 lines of the VICAR label (e.g., using the IUEDAC program label). The best source for this information, however, is still the original observing script.

Note that the above problem does not affect NEWSIPS-processed files.

- Randy Thompson


The IUE Electronic Newsletter, edited by James Caplinger, is primarily intended to inform the numerous remote and local users of the IUEDAC software of recent software updates, as well as let them know about news relating to the IUE project in general. If you want your name to be added to, deleted from, or changed on our distribution list, please send us e-mail to

news@iuedac.gsfc.nasa.gov

or send a postcard to:

IUE Data Analysis Center (IUEDAC)
Code 686.9, NASA-GSFC
Greenbelt, MD 20771


* IUE Data Analysis Center * IUE Project*


Webmaster

Mr. James R. Caplinger, Computer Sciences Corporation

Responsible NASA Organization/Official

Dr. Don West, IUE Operations Scientist