* Astronomy

Messier 79 (also M79, NGC 1904, ESO 487-SC7 and GCL 10) is a magnitude +8.56 globular star cluster located 41,000 light-years away in the constellation Lepus . 
The cluster was discovered by French astronomer Pierre Méchain using a 15.24 cm (6 inch) speculum newtonian reflector on the 26th October 1780.
Charles Messier observed the cluster in December 1780.
M79 was also observed by William Herschel in 1783.

Position (J2000): R.A. 05h 24m 10.6s  |  Dec. -24° 31' 25"

Like Messier 54 (the other extragalactic globular on Messier's list), it is thought that M79 is not native to the Milky Way galaxy at all, but instead to the putative Canis Major Dwarf Galaxy which is currently experiencing a very close encounter with the Milky Way. 
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Title: Constraining the parameters of globular cluster NGC 1904 from its variable star population
Authors: N. Kains, D. M. Bramich, R. Figuera Jaimes, A. Arellano Ferro, S. Giridhar, K. Kuppuswamy

We present the analysis of 11 nights of V and I time-series observations of the globular cluster NGC 1904 (M 79). Using this we searched for variable stars in this cluster and attempted to refine the periods of known variables, making use of a time baseline spanning almost 8 years. We use our data to derive the metallicity and distance of NGC 1904. We used difference imaging to reduce our data to obtain high-precision light curves of variable stars. We then estimated the cluster parameters by performing a Fourier decomposition of the light curves of RR Lyrae stars for which a good period estimate was possible. We also derive an estimate for the age of the cluster by fitting theoretical isochrones to our colour-magnitude diagram (CMD). Out of 13 stars previously classified as variables, we confirm that 10 are bona fide variables. We cannot detect variability in one other within the precision of our data, while there are two which are saturated in our data frames, but we do not find sufficient evidence in the literature to confirm their variability. We also detect a new RR Lyrae variable, giving a total number of confirmed variable stars in NGC 1904 of 11. Using the Fourier parameters, we find a cluster metallicity [Fe/H]_ZW=-1.63 ± 0.14, or [Fe/H]_UVES=-1.57 ± 0.18, and a distance of 13.3 ± 0.4 kpc (using RR0 variables) or 12.9 kpc (using the one RR1 variable in our sample for which Fourier decomposition was possible).

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