Astronomy educator/Sidewalk astronomer
Owner of Astronomy Delight franchise
18 inch f4.42 Dob on eq platform w ST120 f/5 finder
12 inch Zhumell Dob
8 inch f/6.9 home made Dob with Seevers optics
William Optics red 10th Anniversary 80mm FD
C8 XLT on Vixen GPDX
26lb eyepiece box
Cernan Space Center astronomer
Member of Northwest Suburban Astronomers
Quote:I'm wondering just how much smaller brighter and different it was when Messier cataloged it on sept 12, 1758.
First and foremost observing love: naked eye.
Last but not least, telescopes.
And I sometimes dabble with cameras.
Orion xx14g Dob CPC 1100 w/Skywatcher 80ED piggybacked Coronado PST TMB 92L refractor AT Voyager mount Nexstar 6/8 mount Denk Big Easy binoviewers Oodles of eyepieces and other optical gadgets Past scopes Meade 8" reflector and 8" SCT
Quote:Here is an interesting graphic showing the very visible expansion of the crab's visible gas cloud between 1973 and 2000:http://spiff.rit.edu/classes/phys231/crab/crab.html
Quote:Here is an interesting graphic showing the very visible expansion of the crab's visible gas cloud between 1973 and 2000: http://spiff.rit.edu/classes/phys231/crab/crab.html
Nytecam 51N 0.1W Meade 30cm LX200 astrograph+C8+Ha+CaK PSTs+spectrographs SX M9+Lodestar-C+M CCDs/Canon 1100D DSLR My Meade astrograph-colour deepsky My supernova discovery My dome build/spectroscopes/DSO images/Lodestar colour images & videos
Quote:The general assumption is that M1 has been expanding at a fairly constant rate since the light of its progenitor's explosion reached us in 1054. That would make it about 700/960 = 73% of its current size by linear measure.
Tom Polakis Tempe, AZ Visual observing, DSLR photography, lunar & planetary imaging http://www.pbase.com/polakis/
Quote: Very interesting link - especially reference to the old 36" Crossley reflector may me think Mayall's spectra of the Crab expansion was old too eg in 1938? in Wikipeadia thus...
Using his newly built spectrograph, Mayall was the first to determine the radial velocities of many knots of gas in the Crab Nebula. Using these data and the previously published angular rate of expansion of the nebula, he was able to estimate its distance. Consequently, he became the first person to recognize and demonstrate that the Crab Nebula was the remnant of a supernova observed and recorded in 1054 (SN 1054), rather than a classical nova. Walter Baade was instrumental in stimulating and counseling Mayall after around 1939, taking on the role previously filled by Hubble
Sky & Tel Contributing Editor
24" f/3.7 Starstructure
Adventures In Deep Space
7500+ NGC/IC Visual Descriptions
Quote:I think when M1 extends its contrast and magnitude declines because the nebula is more deluted in space.
But we have an advantage compared to Messier, we have OIII filters !
10" F/4.7 Modified Skywatcher Reflector, 38mm Orion Q70, 17mm Modified Ultima LX, 10mm TeleVue Delos, 7mm Pentax XL.
Quote: I don't think an O-III filter is the filter of choice for M-1. I believe the UHC would be better, or none at all IIRC. I did check out your web page and you have some really nice drawings! Love the scopes too!