M33 Tiangulum Galaxy, Big Bright but Low Surface Brightness
M33 Tiangulum Galaxy, Big Bright but Low Surface Brightness
M33 is probably a good visual object as it has a Visual Brightness of 5.7. But as for APer, not so lucky as this object has a listed Surface Brightness of 14.2, only slightly brighter than M101. Why is there a vast difference between these 2 figures ? This is because surface brightness of the object is Total Brightness divide by its surface area, hence, comparing a Star (point source) of mag 5.7 to Triangulum Galaxy, the surface brightness of the later is much dimer after dividing by its large surface area. Now you know why doing an Apparently dimmer M1 crab Nebula is much much easier although it is much smaller ! Attached M33 taken off Elias Road @ Pasir Ris Park on 26 Oct 2013 when the sky decided to suddenly open up for a night !
Last edited by PETER LOO on Thu Nov 21, 2013 11:27 pm, edited 4 times in total.
Re: M33 Tiangulum Galaxy, Big Bright but Low Surface Brightn
Nice shot! Spiral arms spotted. Thanks for sharing info about this object.
http://www.astro.sg
email: gary[at]astro.sg
twitter: @astrosg
"The importance of a telescope is not how big it is, how well made it is.
It is how many people, less fortunate than you, got to look through it."
-- John Dobson.
email: gary[at]astro.sg
twitter: @astrosg
"The importance of a telescope is not how big it is, how well made it is.
It is how many people, less fortunate than you, got to look through it."
-- John Dobson.
Re: M33 Tiangulum Galaxy, Big Bright but Low Surface Brightn
nice. what is the exposure time? is it single snap?
Re: M33 Tiangulum Galaxy, Big Bright but Low Surface Brightn
Thanks Gary & Kimo, Shooting Data, Canon 500D filter mod, ISO 1600 75s X 30 shots, selected 20 + better ones to combine. During capturing, used MaximDL5, selected "save to hard drive" feature to preserve CR2 format instead of using RAW mono. Convert CR2 to TIFF color using Canon Digital Photo Professional that came as a bundle. Stretched the Dark Library built at home as well as the Light Frames collected. Do Dark subtraction in Nebulosity2 with Scale Dark, then combine into 3 groups before off-set the color balance, then combine all. Final stretched.
Vixen GPD2 Mount un-guided, TS-65, below many lamp post at a grass patch in-between Pasir Ris P.A. Chalet & the Rock climbing structure, did it when the scope still pointing North East before crossing Zenith to avoid some of the lamp post lights.
Sky condition: Sky Tansparency very good (post rain), Seeing very bad, can see the stars blinking like crazy, lots of turbulence, a few drops of rain threatening the shooting, windy and caused a lot of "eggy" stars, may be can try the De-convolution feature in MaximDL5 to correct these eggy stars but has not. The vertical noise bars are called Read Noise, might be able to be minimized using proper Averaging Method via software, but easiest for me is to use ISO 800, then don't see them appearing.
Vixen GPD2 Mount un-guided, TS-65, below many lamp post at a grass patch in-between Pasir Ris P.A. Chalet & the Rock climbing structure, did it when the scope still pointing North East before crossing Zenith to avoid some of the lamp post lights.
Sky condition: Sky Tansparency very good (post rain), Seeing very bad, can see the stars blinking like crazy, lots of turbulence, a few drops of rain threatening the shooting, windy and caused a lot of "eggy" stars, may be can try the De-convolution feature in MaximDL5 to correct these eggy stars but has not. The vertical noise bars are called Read Noise, might be able to be minimized using proper Averaging Method via software, but easiest for me is to use ISO 800, then don't see them appearing.