- NYT article: Milky way Galazy is bigger then Andromeda
- Supermassive blackholes discovered (dailygalaxy.com)
- NYT: Postcards from Mars – Photos from NASA’s Mars orbiter
Archive for category Astronomy
Astronomy articles
Jan 11
Observation on 3 Jan
Jan 3
Time: 9:30PM-11:30PM
Great Nebula in Orion (M42):
M42 cleared the water tank around 9:30 PM.
Mag: 4.0.
Alignment: Auto two-star. Betelgeuse (Orion) and Sirius (Canis Major)
Very clear view
Open cluster NGC1981:
Mag: 4.6.
Alignment: not realigned
Very clear view. Almost exactly like in this photo.
Note: Auto two-star align failed later in the night when Orion was almost at Zenith. The eyepiece obstructs movement of the scope when pointed to zenith. Shifted to one-star align (Rigel).
Opencluster M36:
Mag: 6.3
Very faintly visible.
Time: 7-8PM
Dumbell nebula (M27/NGC6853), Mag: 7.3. Alignment star: Altair. Failed
Ring Nebula (M57/NGC6720), Mag: 9. Alignment star: Vega. Failed
Alignment: Jupiter
Globular clusters: M22 (Mag: 5.1), M28 (Mag:6.9). Failed
M20 (Mag: 6.3) . Failed
Lagoon Nebula (M8, Mag: 5) –
Alignment: Jupiter
Nebula like haze covered entire eye piece but could not make out any shape. This nebula has an apparent dimension of 90×40 arch mins. It spans more than 1 deg so can fill entire eye piece. Failed.
Trifid Nebula (M20, Mag: 6.3). Apparent dimension: 28 arc min
Alignment: Jupiter
Time: 9-930 PM
Dumbell Nebula (M27/NGC6853, Mag: 7.3
Time: 10PM – 10:50PM
Great Nebula in Andromeda (NGC 224/M31): Mag 3.5
Alignment star: Mirach (Andromeda)
SUCCESSFUL
Time: 11-11:30PM
Triangulum galaxy (NGC 598/M33) – Mag: 5.7
Apparent dimension: 73×45 arc min
Alignment star: Mothallah (Triangulum)
Failed.
Sky and Telescope article: Fuzzies in Your Future: An Introduction to Deep-Sky Objects
Celestia cheat-sheet
Oct 3
[Shift+left-click+drag] or [,.] (comma,full-stop): Change Field of view
[Ctrl-V] : Changes vertex shading options
[Shift-R]/R : Changes texture mapping
[`] (backtick) : Toggle FPS display. Note if this drops below 6 you may crash
the app
[Home/End] : Move closer/farther
[Cmd-f] : toggle full-screen/window modes
[Ctrl-R]: Split view vertically
[del] : delete active view
[/] : show constellation shapes
[Ctrl-B] : show constellation borders
[U] : Enable galaxies
[Shift+(] and [Shift+)] : Galaxy brightness controll
[Shift+^] : turn Nebulae on/off
[O] : show orbits
[Ctrl-S]: Adjust display of stars
Direction keys: Pitch and yaw
Shift + direction keys: rotate around object
Right click+drag: rotate and change perspective
Links:
Celestia
Telescope terminology
Oct 3
Focal ratio (same as f-stop for a camera) = focal length/aperture
Power (aka magnification) = focal length of telescope/focal length of eyepiece
Field of view = Apparent field of eyepiece / Magnification
Apparent field of view is specified on the eyepiece
The 25mm eyepiece that comes as part of the Celestron NexStar 5SE telescope has an apparent field of view of 50 deg.
Exit pupil:
The circular image or beam of light formed by the eyepiece of a telescope. To take full advantage of a scope’s light-gathering capacity, the diameter of an eyepiece exit pupil should be no larger than the 7mm diameter of your eye’s dark-adapted pupil, so that all of the light collected by the telescope enters your eye. (The eyepiece exit pupil diameter is found by dividing the eyepiece focal length by the telescope focal ratio.) Your eye’s ability to dilate declines with increasing age (to a dark-adapted pupil of about 5mm by age 50 or so). For those in this age group, eyepieces with exit pupils larger than their eyes can dilate to simply waste their telescope’s light-gathering capacity, as some of the scope’s light will fall on their iris instead of entering their eye.
Celestron NexStar 5 SE
Aperture: 5 inches (125mm)
Focal length: 1250 mm
Focal ratio: 10
Limiting Stellar Magnitude: 13
With a 25mm eyepiece Magnification: 50x
Highest useful magnification: 295x (4mm eyepiece)
Lowest useful magnification: 17.86x (70mm eyepiece)
Useful links:
Astronomy Terms
Scope Math
New Yorker article on light pollution and the Bortle Scale