In autumn 1994, two groups of astronomers announced that they had discovered Cepheid variable stars in a distant cluster of galaxies. ... As the term suggests, variable stars change in brightness over time. ... Variable stars are an ideal way to get high-school students doing real science, with real data, from the real sky. ... a sky chart to find the stars . ... Students can use the nearby stars to estimate the magnitude of Delta. ... Locate the star Delta in Cepheus and estimate its brightness . ...

... Tonight's Sky . ... SUN MOON MERCURY VENUS MARS, JUPITER SATURN . ... Observing . ... Why do the constellations and the Moon appear upside down from the Southern Hemisphere? ... From the Southern Hemisphere, any object or constellation that lies near the celestial equator (the imaginary line that divides the northern and southern halves of the sky) would appear both upside down and reversed left to right compared to a northern perspective. ... Get instant access to subscriber content on Astronomy...

Next: Basic Properties Up: R Coronae Borealis Stars Previous: Introduction . RCB stars are named after a star just visible to the naked eye in the constellation of Corona Borealis. RCrB was discovered by Edward Pigott, an English amateur astronomer, who had been observing a star in the `Northern Crown' for over a decade. ... Since 1795, other RCB stars have been discovered and their properties have been carefully observed. ...

... Bad Astronomy . ... Bitesize Astronomy . ... Last week's Snack talked about how black holes can affect the environment around them in such a way as to be very bright . ... It's a common misconception that black holes always have matter swirling into them. ... As this matter gets closer and closer to the black hole it piles up and a large, fairly flat disk forms. This is called the accretion disk , because matter from this disk accretes (that is, falls in) on the black hole. ... 2008 Phil Plait. ...

... The concerns here are similar to those for observing bright targets; saturation and blooming of the bright companion PSF must not impact the faint target. Also, one may need to consider subtracting the PSF of the bright object, and effects which limit the accuracy of that subtraction. If the bright companion will saturate and bloom, it will be necessary to rotate the CCD so that blooming along the CCD columns does not obliterate the faint target. ...

... Observing . ... Home Education Workshops at Adorama Astronomy Workshop: Observing Variable Stars from the City ? February 15, 2015 . ... Beyond New York City . ... Observing Resources for Amateur Astronomers - Part 1: Beginning Observers . ... A History of the First Forty Years of the Amateur Astronomers Association . ... Presented by€а Adorama €аFor the Amateur Astronomers Association of New York . ... 2016 Amateur Astronomers Association of New York Designed by Press Customizr Powered by . ...

... Recurrent Nova RS Ophiuci . ... Such stars are now modeled as interacting binary star systems, composed of a compact white dwarf star co-orbiting with a swollen red giant. ... At an estimated distance of 3,000 light-years, RS Ophiuci is now reported to be fading rapidly. ... Publications with keywords: nova - cataclysmic variable star - white dwarf - red giant - binary star . Publications with words: nova - cataclysmic variable star - white dwarf - red giant - binary star . ... Nova Over Iran . ...

... The following charts/text are intended as tools for monitoring the Type Ia supernovae ( SNe ) event visually or photographically (utilizing telescope equipped CCD equipment).The files include: A replication of The Type Ia SNe , V- magnitude (with data point checks from other cited references)and color index (B-V) templete (to indicate a general color-related trend of the type Ia ... I believe this might help alleviate some of the problems involving the making of acceptable amateur light curves...

... Stars . ... Cepheid variable stars have been known since the 18th century. ... Regularly brightening to a peak over days, weeks or months before fading these variable stars were remarkable curiosities to astronomers in past centuries.€а The term Cepheid is taken from the star Delta Cephei in the constellation of Cepheus, which was identified as variable€а in 1784 by the teenaged prodigy John Goodricke (1764-96). ... Tweets that mention Cepheids: Inconstant Stars which break the rules | ...

An image of the grand design of spiral galaxy M100 obtained with NASA's Hubble Space Telescope resolves individual stars within the majestic spiral arms. ... Hubble has the ability to resolve individual stars in other galaxies and measure accurately the light from very faint stars. This makes space telescope invaluable for identifying a rare class of pulsating stars, called Cepheid Variable stars embedded within M100's spiral arms. ... 617) 495-7062 . Fax: (617) 495-7356 . ...

... STScI-PRC99-19 HUBBLE FINDS VARIABLE STARS IN DISTANT SPIRAL GALAXY A NASA Hubble Space Telescope (HST) view of the magnificent spiral galaxy NGC 4603, the most distant galaxy in which a special class of pulsating stars called Cepheid variables have been found. It is associated with the Centaurus cluster, one of the most massive assemblages of galaxies in the nearby universe. ... Researchers found 36-50 Cepheids and used their observed properties to securely determine the distance to NGC 4603. ...

... A new bright LBV (Luminous Blue Variable) star was detected in M33 galaxy. LBV stars are the most massive stars in the final stages of evolution before exploding in of supernovae. ... The new LBV star (Fig.1) is the seventh in M33. ... It is one of the brightest LBV stars of the M33 galaxy. ... The brightest object is the core of the galaxy, - a compact star cluster comprising a supermassive black hole. The new LBV star N93351 is located down and to the left from the core. ...

... ATNF Home . ... Variable Red Giants in the LMC: Pulsating Stars and Binaries? ... Infrared J and K photometry has been obtained of all red giants in the half square degree region of the LMC bar searched for variables using the MACHO database by Wood et al. ... Possibilities include contact and semi-detached binaries, rotating stars with giant star spots, episodic dust formation, rotationally stabilized non-radial g - modes and strange pulsation modes caused by convection-pulsation interaction. ...

... CEPHEID VARIABLE STARS: A Cepheid variable or Cepheid is a member of a particular class of very luminous, massive variable stars with pulsation periods of 1-70 days. ... The relationship is calibrated using data collected from Cepheids whose distances are determined by other means. ... Browse through the 68 CCD fits images he sent you, using ds9 and locate the Cepheid variable. ... Image credits: ESA - "http://sci.esa.int/science-e-media/img/20/cepheid-variables.jpg" . ...

... The scheduling routines assist in creating an observing list (stored in the startable) from scratch or from another list stored on disk, and computing the visibility of the stars in a specific night and array configuration. The date of observation is taken from the variable date , and the array name from the variable systemid . If these are not defined, defaults are used for date (the next night) and for array (NPOI). ... addstar , stars _char Add one or more stars to the startable. ...

... About ATMoB . ... The Observing Committee is starting an Observing Awards Program to promote observing among the membership of the Amateur Telescope Makers of Boston. ... Participant must be a current member of the Amateur Telescope Makers of Boston . ... To qualify for your Observing Award Certificate, turn in your worksheet and drawings to an ATMoB Observing Committee member or observing@atmob.org . ... This Excel sheet has useful macros. ... Copyright (c) Amateur Telescope Makers of Boston, Inc. ...

... Fractional flux density variations of between 5 and 100 per cent (typically 15-25 per cent) have been detected on a range of time-scales from 1 to 12 years. ... The 151-MHz flux densities have been indirectly scaled to the 6C flux scale. ... Amongst the 72 sources for which the chance of being a true variable is greater than 0.8, typical maximum flux density variations of 15-25 per cent are seen; eight objects show variations greater than 50 per cent, with one source varying by more than 100 per...

The Astronomy Shop . ... AstroGuide | ... Shop | ... Books | Bright Star Atlas . ... Add this accurate and inexpensive star atlas to your collection for thosetimes you want to travel light. ... Web . www.astronomy.net . About Astronomy Net | Advertise on Astronomy Net | ... Unless otherwise specified, web site content Copyright 1994-2016 John Huggins All Rights Reserved . dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET" . are trademarks of John Huggins ...

... In the light curve depicting their observations, definite trends are noted, here is a "thumb-nail" analysis of the the magnitude estimations of the bright SN (1989B) in the galaxy NGC 3627 (M66). ... 10 (IAUC # 4742) 2/25 13.3 16 j 2/27 13.5(*) 18 lc 2/28 13.8 19 p 3/1 13.2 20 w 3/2 13.5 21 a 3/4 13.8 23 p 3/6 13.3 25 c 3/7 13.3 26 c 3/8 14.1 27 m 3/8 13.3 27 r 3/9 13.4 28 c 3/9 14.1 28 m 3/10 13.6 29 j 3/10 14.0 29 a 3/11 13.6 30 c 3/11 13.5 30 r 3/11 13.7 30 s 3/13 [13.69 CCD Mag.] ...

Chapter 11. Specifying OpenGL Environment Variable Settings . ... Several antialiasing methods are available and you can select between them by setting the __GL_FSAA_MODE environment variable appropriately. ... To see the available values for __GL_FSAA_MODE along with their descriptions, run: nvidia-settings --query=fsaa --verbose . The __GL_FSAA_MODE environment variable uses the same integer values that are used to configure FSAA through nvidia-settings and the NV-CONTROL X extension. ...