Image Credit: NASA, ESA, C. McCully (Rutgers U.) et al.
How do you calibrate a huge gravitational lens? In this case the lens is the galaxy cluster Abell 383, a massive conglomeration of galaxies, hot gas, and dark matter that lies about 2.5 billion light years away (redshift z=0.187). What needs calibrating is the mass of the cluster, in particular the amount and distribution of dark matter. A new calibration technique has been tested recently that consists of waiting for supernovas of a very specific type to occur behind a galaxy cluster, and then figuring out how much the cluster must have magnified these supernovas through gravitational lensing. This technique complements other measures including computing the dark matter needed to contain internal galaxy motions, to confine cluster hot gas, and to create the gravitational lens image distortions. Pictured above from the Hubble Space Telescope, galaxy cluster A383 shows its gravitational lens capabilities on the right by highly distorting background galaxies behind the cluster center. On the left is a distant galaxy shown both before and after a recent revealing supernova. To date, calibration-quality supernovas of Type Ia have been found behind two other galaxy clusters by the Cluster Lensing And Supernova survey with Hubble (CLASH) project.
NASA APOD 05-May-14
Located only 8,000 light years away, the Wizard nebula surrounds developing open star cluster NGC 7380. Visually, the interplay of stars, gas, and dust has created a shape that appears to some like a fictional medieval sorcerer. The active star forming region spans 100 about light years, making it appear larger than the angular extent of the Moon. The Wizard Nebula can be located with a small telescope toward the constellation of Cepheus. Although the nebula may last only a few million years, some of the stars being formed may outlive our Sun.
Imaging telescopes or lenses: Takahashi TOA-150
Imaging cameras: QHYCCD QHY 11
Mounts: Software Bisque Paramount MX
Guiding telescopes or lenses: Astro-Tech TSAPO65Q
Software: Maxim DL, PixInsight LE, CCDStack2
Filters: Baader LRGB Ha SII OIII 2″
Accessories: SBIG STI
Dates: Aug. 5, 2013
Integration: 10.7 hours
Author: Steve Yan
AstroPhotography of the day by SPONLI
05 May 2014
The Sun produced six C-class flares since our last bulletin. The source regions were Catania sunspot groups 33, 34 and 36 (NOAA AR 2047, 2049 and 2051 respectively). Catania sunspot group 36 has slightly grown in size and keeps its beta-gamma-delta magnetic configuration. The CME associated to
the long-duration event of 6:12 UT on 3 May apparently is moving to the west, but also has an Earth-directed component. The CME is expected to arrive around 18:00 UT of 6 May. An asymmetric but faint halo CME was observed in LASCO C2 from 20:48 on 3 May, but analysis of coronagraphic imagery reveals it is expected not to be Earth-directed. Flaring activity at C-class level is expected to continue, with a slight chance for M-class flares. ACE observations of the interplanetary conditions show a signature of shock arrival on 3 May, around 16:50 UT. It is probably associated with the CME event of 30 April. Solar wind speed increased to about 380 km/s. The magnitude of the interplanetary magnetic field went maximally 12 nT, with a vertical component that is varying between -9 and 7 nT. Unsettled geomagnetic
conditions were observed in Dourbes (local K=3) and global NOAA Kp went to K=4. Quiet to active conditions can be expected for the next few hours. The situation will then return to quiet conditions. Unsettled to active conditions could be expected due to the arrival of the CME of 3 May from the UT afternoon of 6 May on.
Equipment: Coronado 90 + Imaging Source DMK + LX75
Processing: Photoshop, Avistack 300 frames
Time UT: 15:00
Exposure 1/500 sec.
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