Zobrazeno 1 - 10
of 2 360
pro vyhledávání: '"Willis D"'
More than 70 years ago it was recognised that ionospheric F2-layer critical frequencies $foF2$ had a strong relationship to sunspot number. Using historic datasets from the Slough and Washington ionosondes, we evaluate the best statistical fits of $f
Externí odkaz:
http://arxiv.org/abs/1601.06441
Long-lived (>20 days) sunspot groups extracted from the Greenwich Photo- heliographic Results (GPR) are examined for evidence of decadal change. The problem of identifying sunspot groups which are observed on consecutive solar rotations (recurrent su
Externí odkaz:
http://arxiv.org/abs/0907.4274
Autor:
Ajello, M., Greiner, J., Sato, G., Willis, D. R., Kanbach, G., Strong, A. W., Diehl, R., Hasinger, G., Gehrels, N., Markwardt, C. B., Tueller, J.
We use Swift/BAT Earth occultation data at different geomagnetic latitudes to derive a sensitive measurement of the Cosmic X-ray background (CXB) and of the Earth albedo emission in the 15--200 keV band. We compare our CXB spectrum with recent (INTEG
Externí odkaz:
http://arxiv.org/abs/0808.3377
Autor:
Bodaghee, A., Courvoisier, T. J. -L., Rodriguez, J., Beckmann, V., Produit, N., Hannikainen, D., Kuulkers, E., Willis, D. R., Wendt, G.
Publikováno v:
Astron.Astrophys.467:585-596,2007
Parameters from the literature, such as positions, photoelectric absorption (nH), spin and orbital periods, and distances or redshifts, were collected for all ~500 sources detected by INTEGRAL-ISGRI so far. We investigate where new and previously-kno
Externí odkaz:
http://arxiv.org/abs/astro-ph/0703043
Autor:
McGlynn, S., Clark, D. J., Dean, A. J., Hanlon, L., McBreen, S., Willis, D. R., McBreen, B., Bird, A. J., Foley, S.
The spectrometer aboard INTEGRAL, SPI, has the capability to detect the signature of polarised emission from a bright gamma-ray source. GRB 041219a is the most intense burst localised by INTEGRAL and is an ideal candidate for such a study. Polarisati
Externí odkaz:
http://arxiv.org/abs/astro-ph/0702738
Autor:
Sguera, V., Barlow, E. J., Bird, A. J., Clark, D. J., Dean, A. J., Hill, A. B., Moran, L., Shaw, S. E., Willis, D. R., Bazzano, A., Ubertini, P., Malizia, A.
Fast X-ray Transients (FXTs) are believed to be non-recurrent bright X-ray sources lasting less than a day and occuring at serendipitous positions, they can best detected and discovered by instruments having a sufficiently wide field of view and high
Externí odkaz:
http://arxiv.org/abs/astro-ph/0509018
Autor:
Dean, A. J., Bazzano, A., Hill, A. B., Stephen, J. B., Bassani, L., Barlow, E. J., Bird, A. J., Lebrun, F., Sguera, V., Shaw, S. E., Ubertini, P., Walter, R., Willis, D. R.
INTEGRAL is the first gamma-ray astronomy mission with a sufficient sensitivity and angular resolution combination appropriate to the detection and identification of considerable numbers of gamma-ray emitting sources. The large field of view enables
Externí odkaz:
http://arxiv.org/abs/astro-ph/0508291
Autor:
Barlow, E. J., Bird, A. J., Clark, D. J., Cornelisse, R., Dean, A. J., Hill, A. B., Moran, L., Sguera, V., Shaw, S. E., Willis, D. R., Capitanio, F., Del Santo, M., Bassani, L.
We present the transient nature of INTEGRAL source IGR J17285-2922, identified from a single period of activity during an IBIS/ISGRI Galactic Centre Deep Exposure in September 2003. The source has a maximum detection significance of 14 sigma in the 2
Externí odkaz:
http://arxiv.org/abs/astro-ph/0505405
Autor:
Willis, D. R., Barlow, E. J., Bird, A. J., Clark, D. J., Dean, A. J., McConnell, M. L., Moran, L., Shaw, S. E., Sguera, V.
The true nature of the progenitor to GRBs remains elusive; one characteristic that would constrain our understanding of the GRB mechanism considerably is gamma-ray polarimetry measurements of the initial burst flux. We present a method that interpret
Externí odkaz:
http://arxiv.org/abs/astro-ph/0505097
Autor:
Hill, A. B., Barlow, E. J., Bird, A. J., Dean, A. J., Ferguson, C., Shaw, S. E., Westmore, M. J., Willis, D. R.
The Burst and Transient Source Experiment (BATSE) aboard CGRO monitored the whole sky through 8 NaI(Tl) crystal scintillators sensitive in the 20 keV - 2 MeV energy band continuously from April 1991 until June 2000. Results are presented on the long
Externí odkaz:
http://arxiv.org/abs/astro-ph/0408444