X-ray Images of the Solar Corona from the Skylab S-054 Telescope

The X-ray telescope (experiment S-054) was a grazing incidence
instrument with a spatial resolution of approximately 2 arc seconds on
axis and had six broadband X-ray filters in the 2 - 60 Angstroem
range. The instrument had a spectrographic mode and an imaging
mode. Each X-ray picture is accompanied by a white-light picture which
was coaligned with the X-ray image. The data were recorded on film.
Approximately 6500 frames of film were available on each film
magazine. One camera magazine was used during the first (SL-2) Skylab
mission. Two were used during the second mission (SL-3), and two
magazines were exposed during SL-4. In total, approximately 32,000
solar X-ray exposures were obtained.

This experiment also included a photomultiplier counter consisting of
a NaI crystal of about 5 cm**2 area and a covering window of 5.08 x
10E-5 m (2 mil) of beryllium (Be). The counter operated in two modes:
either the output went through a pulse-height analyzer, which provided
8 channels of counts from 10 keV to 80 keV, or the DC current was
monitored and converted to a number proportional to the logarithm of
the current.

The observations were obtained during the manned missions and also
during the periods in-between. For more details, see the instrument
description.

The six datasets available from NSSDC are described below:

1. Reduced Contrast X-Ray Photographs of the Sun (Third Generation Negatives
on 70-mm Film) NSSDC ID 73-027A-05A

This data set is contained on 70-mm type 5366 film. These data are
third- generation negatives and have been processed to reduce the
contrast (gamma) of the original flight film. This reduction was
necessary to facilitate making paper prints from the negatives. The
density range of this reduced contrast data is about 2.2. The data
are chronologically ordered. Individual frames include a white-light
image of the Sun about 2.54 cm (1 in.) in diameter, an image of the
Sun in soft X rays about 2 cm in diameter, reference marks, and a
diode array indicating experiment parameters (grating and filter
positions, exposure times, a film counter, and date and time of
exposure). In addition, most frames have numbers located outside the
sprocket holes. The original flight film was contained on five
396.24-m (1300-ft) reels of film, each containing about 7000 frames.

Also Supplied:

'Data Analysis Guide to the ATM S-054 X-Ray Spectroscopic Tele-
scope,' no author, November 1975

Data set 73-027A-05B, on microfilm

2. Film Image Catalog (FIC) on 16-mm Microfilm
NSSDC ID 73-027A-05B

This data set is a copy of the film image catalog (FIC) that catalogs
the data obtained by the AS&E X-ray spectrographic telescope
(experiment S-O54). This catalog is a computer listing copied onto
16-mm microfilm. The data appear in 22 columns across each page.
Each data frame, or X-ray picture of the Sun,is described by the data
in one row of this catalog. The columns include: a cross-reference
index to the frame number printed on the film itself, the calendar
date and the Greenwich mean time (UT) to the nearest second of the end
of that frame's exposure, the exposure duration, in seconds, the
filter in place during that exposure, whether the grating was in place
or not, pitch and yaw offsets from the Sun center (in arc - seconds),
and various other housekeeping parameters such as operational mode,
Skylab orbit number, etc. This catalog gives essentially complete
data for all five S-054 film magazines. Any errors are of a minor
nature and should not affect the user.

Also Supplied:

'Data Analysis Guide to the ATM S-054 X-Ray Spectroscopic Tele-
scope,' no author, November l975

3. Synoptic Summary of Data, One Frame per Day, on 70-mm Film
NSSDC ID 73-027A-05C

This data set consists of one roll of 70-mm film containing 163 images
of the Sun taken in solar X rays. All images are filter 3 (no filter,
passbands of 2 to 32 A and 44 to 54 A) with 64-s exposure times.
These images were taken roughly every 24 h (averaging 23.95 +/- 5.31 h
between frames if the 6 gaps larger than 42 h are omitted). Each
frame includes the white-light image taken prior to the X-ray
exposure, since the corresponding white-light image is offset on the
film. The date of each frame and its location (1 through 163) on the
film are listed next to each frame. The documentation cross-
references the frame location, the date and time, and the frame number
in the film image catalog (data set 73-027A-05B).

Also Supplied:

'Data Analysis Guide to the ATM S-054 X-Ray Spectroscopic Tele-
scope,' no author, November l975

Film image catalog (NSSDC ID 73-027A-05B)

'Frame Catalog for NSSDC Data Sets 73-027A-05C and 73-027A-05D'

4. Synoptic Summary of Data, One Frame per Day, on 35-mm Film
NSSDC ID 73-027A-05D

This data set consists of one reel of 35-mm film containing 163 images
of the Sun taken in solar X rays. All images are filter 3 (no filter,
passbands of 2 to 32 A and 44 to 54 A) with 64-s exposure times.
These images were taken roughly every 24 h (averaging 23.95 +/- 5.31 h
between frames if the 6 gaps larger than 42 h are omitted). The date
of each frame and its location (l through 163) on the film are listed
next to each frame. The documentation cross-references the frame
location, the date and time, and the frame number in the film image
catalog (data set 73-027A-058).

Also Supplied:

'Data Analysis Guide to the ATM S-054 X-Ray Spectroscopic Tele-
scope,' no author, November l975

Film image catalog (NSSDC ID 73-027A-05B)

'Frame Catalog for NSSDC Data Sets 73-027A-05C and 73-027A-05D'

5. Selected Flare Data, Set 1
NSSDC ID 73-027A-05E

This data set, contained on 70-mm black and white film, is also
available on 35-mm film and includes only data relevant to the
following six solar f1ares: June 15, 1973, at 1413 UT; July 29, 1973,
at 1330 UT; August 9, 1973, at 1553 UT; September 5, 1973, at 1834 UT;
September 7, 1973, at 1203 UT; and January 21, 1974, at 2320 UT. The
data include samples taken around 24, 18, 12, and 6 h before the flare
in question, all data taken from 1 h before through 2 h after the
flare, and data samples taken at 6, 12, 18, and 24 h after the flare.
This is a subset of 73-027A-05A and was generated at NSSDC.

Also Supplied:

'Data Analysis Guide for the ATM S-054 X-Ray Spectrographic Tele-
scope,' no author, November 1975

Data set 73-027A-00G (miscellaneous ATM supporting documents)

'Supporting Documentation for ATM Flare Subset Film (73-027A-05E)'

6. Digitized Solar X-ray Coronal Images
NSSDC ID 73-027A-05F

The X-ray images were scanned with a microdensitometer at American
Science & Engineering. Approximately 3000 scanned images were produced
from the 35,000 original photographs. The digital data were stored on
magnetic tapes. In 1990, these tapes were received by NSSDC. Due to
age, not all of the tapes were readable, but the readable tapes were
copied to IBM 3480 tape cartridges. Paper catalogs of these images
may be accessed through standard NSSDC request channels, and digitized
versions of most of the scanned images are available for image
processing. The scans vary in size; the full disk images are 1234x1244
pixels or 1400x1401.

7. Digitized Solar X-ray Coronal Images
NSSDC ID 73-027A-05G

For the PC user a data set comprising C-language programs for
converting the images into a form that can be displayed with graphics
adapters that display 320x200 images in 256 colors (standard with
graphics cards). This Demo diskette also includes two images.