Celestial Atlas
PGC 64000 - 64499 ←PGC Objects: PGC 64500 - 64999 Link for sharing this page on Facebook→ PGC 65000 - 65499
Click here for Introductory Material
Page last updated Oct 28, 2019
Added entries for PGC 64801 and 64805

PGC 64801 (and with
PGC 64805 = PGC 3325401 = Arp-Madore 2026-424)
A magnitude 14.6 spiral galaxy (type (R)SA(r?)ab? pec) in Microscopium (RA 20 29 32.4, Dec -42 30 23)
Physical Information: The pair of galaxies have nearly identical recessional velocities (15565 km/sec for PGC 64801 and 15485 km/sec for PGC 64805), and are obviously strongly interacting (in fact, the pronounced ring suggests that they had a recent head-on collision), so the appropriate recessional velocity for estimating their distance is their average recessional velocity of 15525 km/sec. Given that (and H0 = 70 km/sec/Mpc), a straightforward calculation indicates that the pair is about 720 to 725 million light years away. However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the pair was about 680 million light years away at the time the light by which we see it was emitted, about 695 to 700 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). (The HST press release states that the distance is 704 million light years, but for objects at such distances, such an apparently accurate value is impossible, so for all practical purposes that value is the same as the one just derived.) Based on the Hubble distance and its apparent size of about 0.25 by 0.25 arcmin (all apparent sizes for the two galaxies are based on the HST images), the core of PGC 64801 is about 50 thousand light years across, while the ring surrounding the pair, which has a size of about 0.95 by 0.65 arcmin (plus a little more with the faint extension on the southeastern side) is about 185 to 190 thousand light years across. With PGC 64805, PGC 64801 is used by the Arp-Madore Catalog of Southern Peculiar Galaxies and Associations as an example of a galaxy with a thin ring and centered nucleus, with a companion in the ring (classes 6b and 6.7). PGC 64801 is also listed as ESO 285-19, but the position given for that object suggests that the eastern companion may not have been noticed.
DSS image of region near spiral galaxy PGC 64801 and lenticular galaxy PGC 64805, which comprise Arp-Madore 2026-424 and PGC 3325401
Above, a 12 arcmin wide DSS image centered on PGC 64801 and 64805
Below, a 1.2 arcmin wide DSS image of the pair
DSS image of spiral galaxy PGC 64801 and lenticular galaxy PGC 64805, which comprise Arp-Madore 2026-424 and PGC 3325401
Below, a 1 by 1.25 arcmin wide image of the pair
(Image Credit NASA, ESA, J. Dalcanton, B.F. Williams, and M. Durbin (University of Washington))
HST image of spiral galaxy PGC 64801 and lenticular galaxy PGC 64805, which comprise Arp-Madore 2026-424 and PGC 3325401
Below, a 0.3 by 0.35 arcmin wide image of the core of PGC 64801 (Image Credit as above)
HST image of spiral galaxy PGC 64801

PGC 64805 (and with
PGC 64801 = PGC 3325401 = Arp-Madore 2026-424)
A magnitude 15(?) lenticular galaxy (type (R)SB0/a? pec) in Microscopium (RA 20 29 33.6, Dec -42 30 24)
Physical Information: The discussion of the distance in the entry for PGC 64801, which is undoubtedly at the same distance, given the nearly identical recessional velocities and obvious interaction of the galaxies (in fact, the pronounced ring suggests that they had a recent head-on collision) shows that the pair was about 680 million light years away at the time the light by which we see it was emitted, about 695 to 700 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Based on the Hubble distance and its apparent size of about 0.25 by 0.15 arcmin (all apparent sizes from the HST images), the core of PGC 64805 is about 50 thousand light years across, while the ring surrounding the pair, which has a size of about 0.95 by 0.65 arcmin (plus a little more with the faint extension on the southeastern side) is about 185 to 190 thousand light years across. With PGC 64801, PGC 64805 is used by the Arp-Madore Catalog of Southern Peculiar Galaxies and Associations as an example of a galaxy with a thin ring and centered nucleus, with a companion in the ring (classes 6b and 6.7).
HST image of lenticular galaxy PGC 64805
Above, a 0.225 by 0.4 arcmin wide image of PGC 64805; for wider-field images see PGC 64801
(Image Credit NASA, ESA, J. Dalcanton, B.F. Williams, and M. Durbin (University of Washington))
Celestial Atlas
PGC 64000 - 64499 ←PGC Objects: PGC 64500 - 64999→ PGC 65000 - 65499