NGC/IC Project Restoration Effort

===== NGC 1170 may have been the tail of a comet. It was found by C.S. Pierce at Harvard on the last day of 1869, and was verified by Joseph Winlock. The Notes for the observation in Harvard Annals, Vol. 13, Part 1, reads, "J.W. and C.S.P. independently think the sky generally bright f and a little n of the comet for 14' or more (several fields according to C.S.P.). [The approximate place in Table VIII results from comparison with the comet.]" The comment in square brackets is from the author of the paper, probably J.W. In Table VIII, the only information is the position 02 54 10, +26 31 (1860), and the Remark, "Comet 1869 III p neb 2m 31s, a little s." I haven't yet done the library work to know if the comet's tail stretched off to the northeast from the head. But the description makes it possible that this is the correct explanation for this NGC entry. ----- Using JPL's HORIZONS ephemeris generator in August 2016, I found that the position of the comet was pretty well verified by the observation. For J2000, assuming that the observation took place on 30 December 1869 UT at around 04:00 (31 December at 23:00 EST) then the position of the comet would have been 03 00 06.0, +27 04 15. That would make the position of the nebula 03 02 37, +27 04 for J2000, just 11 seconds larger than the position given by Pierce and Winlock. Given their description of the size of the nebula, I am still of the opinion that they actually saw the faint tail of the comet. Unfortunately, HORIZONS does not give the orientation of the tail. But if we assume that the tail points away from the sun on the sky as well as in space, we can work out an approximate orientation. On 31 December, the sun is in Sagittarius near 18 50.0, -23 00 +-. So the tail, under these assumptions, would indeed be stretching toward the northeast. Perhaps a search of the observations of the comet (called "11P/Tempel-Swift- LINEAR" in modern parlance, "1869 III" in the nomenclature of the day, and sometimes "1869 c") could confirm or falsify this idea.