The night sky atlas is an interactive map of the entire night sky.
It allows viewing any part of the sky and creating sky chart images and PDF printouts.
The default atlas view is tonight's point in the sky approximately opposite to the sun.
It is visible tonight, during most of the night from anywhere on Earth except near the poles.
The declination defaults to 15°N only for convenience, just enter
your geographic latitude
for the declination to see what's directly overhead at midnight tonight.
Then add or subtract 1 hour to the default right ascension value to see what's visible
each hour after or before midnight, respectively.
Monthly visibility of the current view is displayed in the text above a view image.
Visibility is derived from the right ascension value of the current view, and may
require some adjustment for locations far from the equator.
Locations at latitudes above 30°N or below 30°S have the Earth's axis significantly above the horizon.
That results in the nightly motion of the stars near one pole becoming circumpolar around it,
and other stars near the opposite pole are never visible from the same location.
A perfect example are the stars in Ursa Minor, visible all year only from latitudes 30°N and farther North,
yet it is best viewed when reaching it highest altitude in May at midnight.
The form fields and ranges:
| right ascension: | 0 to | 24 | hours | (J2000 equinox & epoch) |
| declination: | -90 to | +90 | degrees | (J2000 equinox & epoch) |
| viewing angle: | 0 to | 180 | degrees | (image diagonal field of view) |
| view twist: | -360 to | +360 | degrees | (rotation about image center) |
| image width: | 75 to | 2000 | pixels | |
| image height: | 75 to | 2000 | pixels | |
| (All values are in decimal format.) |
Display features link parameters:
| b00=1 | If not present, forces all options to true |
| b01=1 | Star name labels |
| b02=1 | Greek Bayer designation letters |
| b03=1 | Milky Way galaxy on charts |
| b04=1 | Constellation stick figures |
| b05=1 | Constellation borders |
| b06=1 | Constellation names |
| b07=1 | Messier objects |
| b08=1 | NGC objects |
| b09=1 | Sun/planets ecliptic line |
| b10=1 | Months on ecliptic |
| b11=1 | Coordinate grid |
| b12=1 | Sky location info & crosshairs |
| (Omit a parameter entirely to turn off a display feature.) |
Images are produced in PNG format for lossless image compression and fast transmission.
PDF files are available in color for viewing and printing on color printers, and also
in monochrome for high-quality printouts on black & white only laser printers.
Some color changes are made to account for the white paper background.
Layouts are sized to fill a standard 8.5"x11" sheet, avoid resizing to preserve the print scale.
The Milky Way is always excluded from monochrome PDFs.
TIP: set the viewing angle to exactly 13.8173 degrees to produce printed PDF charts at a scale of 1 degree per inch.
The printout can be used to measure exact TFOV's (true field of view) of any telescope by merely locating any two stars
at the edge of the eyepiece view, the TFOV angle in degrees will be equal to the distance in inches of the two stars on the chart.
Terms used in star tables
| Related HR Entry | A number indicating additional related HR stars which may be true or optical binaries/multiples |
| CPM | Common proper motion |
| Components Count | The total number of components making up a star (2 for binaries) |
| SB | Spectroscopic binary star detectable by analyzing its spectrum |
Object type codes in NGC, IC, and Messier tables
(Consist of a object category number and one or more object type codes)
| 1 | Galaxy |
| 2 | Galactic nebula (as known when discovered), Supernova remnant |
| 3 | Planetary nebula |
| 4 | Open cluster |
| 5 | Globular cluster |
| 6 | Part of galaxy |
| 9 | Star(s) |
| |
| *, *2, .. ,*Grp | Star, double star, multiple star, asterism or group |
| C, D, E, I, P, S | Galaxy: compact, dwarf, elliptical, irregular, peculiar, spiral (d=dwarf, B=bar, R=ring , M=mixed) also letters from Hubble type or its extensions |
| R.., PRG | Ring galaxy, Polar ring galaxy |
| GxyP | Part of galaxy |
| OCL | Open cluster |
| GCL | Globular cluster |
| DN, EN, RN, PN | dark nebula, emission nebula, reflection nebula, planetary nebula |
| SNR | Supernova remnant |
The author of The Night Sky Atlas is Gill Couto and can be reached at
gillcouto@gmail.com for any info.
All data source credits go to their respective authors/maintainers.
Enjoy!
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