STAR Atlas:PRO™ frequently asked questions - FAQs
Can I list the individual galaxies that make up each Hickson Compact Galaxy Group ?
Yes, with STAR Atlas:PRO you can do exactly that. Follow the procedure below to see how simple this information can be found.
1. Start STAR Atlas:PRO
2. click [Locate] or L on keyboard
3. click the menu option [10] - Hickson Compact Groups of Galaxies
4. Hickson Group Number 1 is the first Hickson Compact Group to be displayed. The bottom half of this information panel displays the Member Galaxies ( the individual Galaxies that make up each Hickson Compact Group).
Upon further study, you will see there is much astrophysical data displayed about each of the Member Galaxies.
The grid in which this information is displayed may be scrolled left to right before all the data can be seen (there is too much to fit on one screen).
5. if you wish to locate the information for another Hickson Compact Group then choose the [Find] button (bottom of information panel) and then enter the number of the Hickson Compact Group of Galaxies ( i.e. try Group number 52 )
Additional Information - (advanced users):
Following is a description of the information displayed about each Hickson Compact Group of Galaxies ( from the STAR Atlas:PRO Manual)
This is the information listed for each Hickson Compact Group of Galaxies.
| Group Type | A two-character code (a letter followed by a number) classifies the group according to its 2 brightest members: S The brightest galaxy is a spiral galaxy. E The brightest galaxy is not a spiral galaxy. 1 m(b) - m(a) >= 1.0 2 0.5 <= m(b) - m(a) < 1.0 3 m(b) - m(a) < 0.5 where m(a) and m(b) are the estimated red magnitudes of the brightest and second brightest members, respectively, of the cluster. | |
| Member Count | Number of galaxies in the group. Only those galaxies within three magnitudes of the brightest galaxy are counted as members. | |
| Angular Size | Angular diameter, in arc minutes, of the smallest circle containing the geometric centers of all galaxies in the group. | |
| Total Magnitude of Group | Total estimated red magnitude of those galaxies counted as group members | |
| Magnitude of Brightest member | Estimated red magnitude of the brightest galaxy. | |
| Redshift | Corrected redshift of the brightest galaxy | |
| Other Catalogues | Other designations of the galaxy group. | |
| Common Positional Data | Common information to all Catalogues. Includes RA, DEC, ALT. AZ. RISE, SET, TRANSIT. | |
This is the information listed for each member galaxy of a Hickson Compact Group of Galaxies.
| Component | Galaxy in HCG group (a-i) |
| Semi-major | Semi-major axis at 25.0mag/arcsec^2^ isophote |
| Semi-minor | Semi-minor axis at 25.0mag/arcsec^2^ isophote |
| Hubble Morphological | Hubble Morphological type |
| Numerical | Numeric morphological type |
| Heliocentric | Heliocentric velocity |
| Est. rms | Estimated rms in Rvhel |
| Bmag | B magnitude within 24.5mag/arcsec^2^ isophote |
| Dia 24.5mag | Diameter of B=24.5mag/arcsec^2^ isophote |
| R mag 24.5 | R magnitude within 24.0mag/arcsec^2^ isophote |
| Dia of r=24.5 | Diameter of R=24.0mag/arcsec^2^ isophote |
| Colour 24.5 | Colour within the 24.5mag/arcsec^2^ isophote |
| BT asymptotic | B_T_ asymptotic magnitude |
| BT asymptotic mag ext | B_T_ asymptotic magnitude corrected for internal and external extinction |
| Abs Mag | Absolute magnitude of individual galaxies, h=H0/100, H0=Hubble constant |
| Names | Other names |