Engineering Papers⌕ Search

Engineering topics

Ulmer, M. P.

Publications and source records attributed to Ulmer, M. P..

66 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Observations of the 4.8-hour variations of Cygnus X-3 above 7 keV from the OSO-7

Results of observations made (during the period from June 30 to July 5, 1972) of Cyg X-3 with the UCSD OSO-7 X-ray telescope in the range from about 7 to 100 keV. The 4.8-hour variation was detected in the 6.6-21.2 keV range, and the ratio of high intensity to mean intensity was 1.52 plus or minus 0.16. In the 21.2-97.8 keV range no 4.8-hour variation in phase with the 6.6-21.2 keV variation could be detected, and the ratio at the phase of high intensity to the mean intensity was 0.6 plus or minus 0.4.

Ulmer, M. P.↗
NASA NTRS1974

Long-term observations of Cygnus X-2 from OSO-7

Results of observations of Cygnus X-2 are reported that were made with an X-ray telescope on board the OSO-7 satellite during the three intervals of January 9-16 and 21-26, 1972, and July 8-11, 1972. Random factor-of-two variations were found in the data. No statistically significant periodic variations were found in the range from 10 hours to 2 days.

Ulmer, M. P.↗
NASA NTRS1974

Extended observations of higher than 7-keV X-rays from Centaurus X-3 by the OSO-7 satellite

The UCSD X-ray telescope on board OSO-7 provided 43 days of continuous coverage of the variable X-ray source Cen X-3 at energies above 7 keV during December 1971 and January 1972. We detected the 4.8-sec pulsation period, the 2.087-day eclipse cycle, and an apparently nonperiodic, low-intensity state lasting more than 12 days. Spectra obtained over the 7-30 keV range during noneclipsed high-intensity states are steeper than those previously reported. Large changes, which may be characterized by a number spectral index alpha varying between 3.0 plus or minus 0.2 and 2.0 plus or minus 0.3, or by exponential spectra with kT varying from 6 plus or minus 2 to 13 plus or minus 3 keV, occur at different high-intensity states.

Baity, W. A.↗
NASA NTRS1973

The direction and spectral variability of a cosmic gamma-ray burst

Description of the simultaneous observations of a gamma-ray event by five different satellites on May 14, 1972 in widely differing geomagnetic environments. The direction of the source was unambiguously determined, and it is concluded that the event was real and not caused by some unexplained spurious or instrumental effects. Since the obtained direction is far from the earth and the sun, the conclusion is that this gamma-ray event was almost certainly of cosmic origin. The total energy at the earth in this event was about .0005 ergs/sq cm from 11 to 1500 keV.

Wheaton, W. A.↗
NASA NTRS1973

New transient source, Cepheus X-4, observed by OSO-7.

A new, apparently transient, X-ray source, Cep X-4, was observed from June 20 to July 7, 1972, by the UCSD X-ray telescope on OSO-7. Subsequent observations by the lower-energy MIT X-ray telescope on the same satellite confirmed the source and provided an improved position of alpha = 21 hr 37 min, delta = 56.78 deg (1950 coordinates) with an error circle radius of about 0.4 deg. Best fits to the UCSD data in the 7- to 37-keV range were obtained on June 20 to 28 and June 29 to July 6, 1972, respectively.

Ulmer, M. P.↗
NASA NTRS1973

Observations of the binary X-ray source SMC X-1 from OSO-7.

The X-ray source was observed with an X-ray telescope during the time from April 15, 1972 to May 25, 1972. These observations complement the Uhuru results reported by Schreier et al. (1972) and permit an extension of the spectrum to at least 35 keV. Combined with other observations, the data could help determine long term periodic variations, if any exist. The relative exposure and the corrected counting rate of the X-ray telescope during the precession of the satellite axis are shown in a graph.

Ulmer, M. P.↗
NASA NTRS1972

Hard X-ray observations of Hercules X-1 by OSO-7.

The X-ray source Her X-1, identified as a pulsating, eclipsing X-ray source, was observed by the UCSD X-ray telescope on the OSO-7 satellite. A three-point spectrum for Her X-1 was determined on the basis of data obtained when the source was in its high-intensity state. Errors in the UCSD result due to uncertainties in the gain and in converting counts per second to photon flux are about 20%.

Ulmer, M. P.↗