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تسجيل مستخدم جديدFirst Study of Combined Blazar Light Curves with FACT and HAWC
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For studying variable sources like blazars, it is crucial to achieve unbiased monitoring, either with dedicated telescopes in pointing mode or survey instruments. At TeV energies, the High Altitude Water Cherenkov (HAWC) observatory monitors approximately two thirds of the sky every day. It uses the water Cherenkov technique, which provides an excellent duty cycle independent of weather and season. The First G-APD Cherenkov Telescope (FACT) monitors a small sample of sources with better sensitivity, using the imaging air Cherenkov technique. Thanks to its camera with silicon-based photosensors, FACT features an excellent detector performance and stability and extends its observations to times with strong moonlight, increasing the duty cycle compared to other imaging air Cherenkov telescopes. As FACT and HAWC have overlapping energy ranges, a joint study can exploit the longer daily coverage given that the observatories locations are offset by 5.3 hours. Furthermore, the better sensitivity of FACT adds a finer resolution of features on hour-long time scales, while the continuous duty cycle of HAWC ensures evenly sampled long-term coverage. Thus, the two instruments complement each other to provide a more complete picture of blazar variability. In this presentation, the first joint study of light curves from the two instruments will be shown, correlating long-term measurements with daily sampling between air and water Cherenkov telescopes. The presented results focus on the study of the variability of the bright blazars Mrk 421 and Mrk 501 during the last two years featuring various flaring activities.
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Probing the high energy emission processes of blazars through their variability relies crucially on long-term monitoring. We present unprecedented light curves from unbiased observations of very high energy fluxes from the blazars Mrk 421 and Mrk 501
based on a joint analysis of data from the First G-APD Cherenkov Telescope (FACT) and the High Altitude Water Cherenkov (HAWC) Observatory. Thanks to an offset of 5.3 hours of the geographic locations, a complementary coverage of up to 12 hours of observation per day allows us to track variability on time scales of hours to days in more detail than with single-instrument analyses. Complementary features, such as better sensitivity thanks to a lower energy threshold with FACT and more regular coverage throughout the year with HAWC, provide valuable cross checks and extensions to the individual analyses. Daily flux comparisons for both Mrk 421 and Mrk 501 show largely correlated variations with a few significant exceptions. These deviations between measurements can be explained through fast variability within a few hours and will be discussed in detail.
We present detailed optical photometry for 25 Type Ibc supernovae within dapprox150 Mpc obtained with the robotic Palomar 60-inch telescope in 2004-2007. This study represents the first uniform, systematic, and statistical sample of multi-band SNe Ib
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Blazars are among the most powerful extragalactic objects, as a sub-class of active galactic nuclei. They launch relativistic jets and their emitted radiation shows strong variability across the entire electro-magnetic spectrum. The mechanisms produc
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Only five binary systems have been found to emit at TeV energies. Each of these systems is composed of a massive O or B type star and a compact object (black hole or a pulsar). The type of compact object and the origin of the gamma-ray emission is un
known for most of these systems. Extending spectral observations to higher energies can help disentangle the nature of the compact object as well as the particle acceleration mechanisms present. Interestingly, the TeV emission from these systems does not always coincide with their emission in GeV or X-ray, which is how many such systems have been originally discovered. Increased coverage of these systems may allow HAWC to see precisely when in the orbit the TeV emission begins and ends. The HAWC Observatory detects TeV gamma-rays with high sensitivity, covering over two-thirds of the overhead sky every day. Applying a stacking method to known TeV binary systems can help HAWC enhance the signal from TeV binaries above the steady background from other sources in the galaxy. We will present results from this stacking analysis using 760 days of HAWC data.
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