Astronomy. How do I figure out what star is at a certain point?

Does anyone know what star is at 3h 8m 17.8s; DEC=40 degrees, 57' 52.4';? Supposedly this is a well known star and is eclipsed sometimes. Can anyone help with this? Thanks.Astronomy. How do I figure out what star is at a certain point?
It is Algol in Perseus, also known as Beta persei. I took some time with this thinking it was a trick question. You didn't give the + or - for the Declination so I checked the southern hemisphere too. Nothing there.





Your coordinates match up pretty closely, within a few seconds, of the J2000 coordinates below. Note that the J2000 coordinates do NOT correspond to TODAY's coordinates which we call ';epoch of date'; (meaning in this case July 7 2007). But ya know, it's close enough, you bring up the star chart, there's Algol.





As previously noted by the first man up with the answer, Algol is an eclipsing binary. It is about 22.5 degrees off the ecliptic which is way too far to be ';eclipsed'; (occulted) by planets, the moon, sun, etc. So the ';eclipsing'; reference you got had to be about the binary aspect.





This is an easy star to find with a planisphere. You start with Cassiopeia ';the W'; then move ';down'; to Perseus. The double cluster should appear as a faint patch (in a good sky) and is a wonderful binocular and small telescope object. Perseus has an *intense* galaxy cluster that is spectacular in a small telescope and surprisingly often overlooked by amateur astronomers.





I have given you below all the data from Sky Map Pro v. 11 on Algol which is more than almost anyone wants to know about Algol.





The Wiki link is a good stick-figure of the constellation. You can see the double cluster in the upper right and still further you see the bottom of one part of the constellation Cassiopeia, near the object M103.





Hope that helps,





GN








Sky Map Pro summary


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Information about beta Persei


Summary


Maximum magnitude: 2.12


Minimum magnitude: 3.39


Type of variability: EA/SD


Spectral type: B8V


Distance: 92.8 +/- 2.3 light years





Position information for 07 Jul 2007 11:03:21 PM


JD: 2454289.62733


Apparent RA: 03h 08m 38.84s


Apparent Dec: +40掳 59' 01.1';


Constellation: Perseus


Altitude: -1掳 55' 2';


Azimuth: 22掳 37' 41';


Hour angle: 14h 2m 29s


Rise: 23h 21m 14s


Transit: 9h 3m 9s


Set: 18h 41m 9s





Names and Catalog Numbers


Proper name: Algol


Bayer letter: b Persei


Flamsteed number: 26 Persei


GCVS designation: beta Persei


Tycho catalog number: TYC 2851-2168-1


Hipparcos catalog number: HIP 14576


PPM catalog number: PPM 45864


SAO catalog number: SAO 38592


HD catalog number: HD 19356


Bright star number: HR 936


BD number: BD +40 0673


WDS designation: BU 526





Star atlas chart numbers


Herald-Bobroff Astroatlas: Chart C-37


Millennium Star Atlas: Charts 99-100 (Vol I)


Sky Atlas 2000.0: Chart 4


Uranometria 2000: Chart 63, Vol 1





Display Yale Bright Star Catalog record


Display Hipparcos record


Display Tycho 2 Catalog record


Display WDS Catalog record


Display binary star orbit record


Display GCVS Catalog record








Yale Bright Star Catalog Data


Preliminary Version of the Bright Star Catalogue, 5th Revised Edition. Dorrit Hoffleit, Department of Astronomy, Yale University, Wayne H. Warren Jr., ST Systems Corporation, National Space Science Data Center, NASA Goddard Space Flight Center (1991)


Identification


Bright star catalog number: HR 936





Position


RA (J2000.0): 03h 08m 10.1s


Dec (J2000.0): +40掳 57' 20';


RA (B1900.0): 03h 01m 39.5s


Dec (B1900.0): +40掳 34' 14';





Galactic coordinates (system II)


Longitude: 148.98掳


Latitude: -14.90掳





Magnitude and spectral information


Magnitude: 2.12 [V on UBV (Johnson) system]


B-V on Johnson system: -0.05


U-B on Johnson system: -0.37


R-I: -0.03 (on Johnson system)


Spectral type: B8V





Annual proper motion for J2000.0 on FK5 system


RA: +0.004';


Dec: -0.001';





Parallax and radial velocity


Trigonometricparallax: +.045';


Heliocentric radial velocity: +004 km/sec


Radial velocity comments: Spectroscopic binary; Orbital data available


Projected rotational velocity (v sin i): 65 km/sec





Double/Multiple star information


ADS catalog number (Aitken 1934): ADS 2362





Component data


Identification: AD


Magnitude difference: 8.3


Separation: 81.9';


Total number known: 6





Cross references to other catalogs


Variable star designation: Bet Per


Durchmusterung: BD+40 673


Henry Draper catalog: HD 19356


SAO catalog: SAO 38592


FK5 catalog: 111


Infrared source: NASA Merged Infrared Catalogue, Schmitz et al. 1978.





Remarks


Colours: Color excess E(B-V) = +0.03.


Double/multiple stars: A* var. B8V, 1.858y, a = 0.011'; or 1.862y, a = 0.104';. Apparent apsidal period 28.4y or 32y. Resolved by speckle interferometry: sep. 0.086';, 2-3v fainter than primary. This may be Algol C. Four visual companions all optical: B, 12.7v at 59';; C, 12.5 at 67';; D, 10.5 at 82';; BC sep. 15';; E, 12.5v at 11'; from D.


Miscellaneous: One of the few known galactic radio sources in which the dominant star is normal. 21cm radio source.


Names: ALGOL; Gorgona; Gorgonea Prima; Demon Star; El Ghoul.


Spectra: B8V+G.


Spectroscopic binary: Algol ABxC: 1.8613y, K 12.0k/s, V0 +3.7k/s, msin3i 3.91, asini 109. Spectra B8V, G5IV, Am. Mass Algol AB, 5.3 Suns; C, 1.8 Suns. Circumstellar gas fills Roche lobe of hot component. ADS 19356A: 2.8673d, K 44.0k/s, V0 var., asini 1.73. Resolved by speckle interferometry 1982.17, sep. 0.052';, 1983.94, sep. 0.08';.


Variability: ADS 2362A is the prototype Algol star, first discovered as variable by Montanari in 1669. The first period determined by Goodricke in 1783, who also interpreted the variations as due to eclipses. The prototype star proves to be a more a complicated system than most of the Algol-type stars, i.e., compact triple system with separation of the components well under 0.1';. The components usually designated Algol A, B, C, sometimes A, a, P. Two formerly additionally desig- nated components D and E, inferred on the basis of an apparent 32 year apsidal motion, are now considered spurious. The various Algol components must not be confused with the visual components ADS 2362 B-E, optical companions at much greater distances from A. ADS 2362A, EA 2.12 - 3.40V, 2.86732442d, abrupt period changes. Orbital and rotation periods synchronized. Rotational velocity 65k/s. Radio flares extending to about 1 A.U., not associated with X-ray activity. Radio flare activity appears correlated with period discontinuities, attributed to ';starquakes.'; Mass flow from K to B8 component at rate of 1.8x10E-08 solar masses/year. Possible circumstellar material associated with radio or H alpha emission.Astronomy. How do I figure out what star is at a certain point?
Get a copy of 'Red Shift,' you will have all the information you will ever need.
Stars do not eclipse, except when they are BINARY with a companion, such as ALGOL





ALL stars are charted and found in books like the Handbook of the Royal Astronomical Society of Canada.
The only bright star near that location that I see is Algol (RA=3h, 8m, 40s; Dec=40掳, 59', 10s). It is a well-known eclipsing binary.
man try nasa.gov web site