Digital Imaging of a Compact Extragalactic Cluster Exhibiting Interaction, Starburst Regions and Redshift Anomaly

Principal Investigator : Thomas J. Teters
City: Ft. Collins
State: CO
Zip Code: 82524

Scientific Category: Clusters of Galaxies & Red-Shift

Abstract: Considerable uncertainty exists concerning the nature of the interactions between the
component galaxies of Seyfert's Sextet, NGC 6027. With its high resolution and spectral imaging
capabilities, the Hubble Space Telescope can effectively be used to better understand these
interactions, specifically that of component 'd', which appears to have a much higher redshift
than the rest of the group. Critical to this study is the accurate determination of distance to
the group, aided by an independent process of determining the special characteristics of the
larger globular clusters, present in and between the group members

Scientific Keywords: Seyfert galaxy, globular cluster, redshift, compact galactic group,
ultraviolet excess galaxy

Estimated Observing time 3.5 hours (primary)
3.5 hours (parallel Number of targets
Objects to observe 1 (primary)
2 (parallel)

Filters requested: 439W   F555W w/ POL 60   675W   791W   850LP
Special Scheduling requests: July-August 1997

Question #1  Explain in detail what you are proposing to study and the significance of the
investigation to the field of astronomy.

This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France)
reveals that very little research has been done on the group of interacting galaxies known as
Seyfert's Sextet, NGC 6027. The distance, age, and dynamics of this system remain to be
satisfactorily determined. Several anomalous characteristics are already known: One galaxy
(component 'd') is believed to have a redshift 4.7 times as great as the other five members of
the group, yet appears to be interacting with the rest of the group; the recession speed needs
to be confirmed by other means than redshift, and the nature of the interaction identified. Also,
there are objects between components 'a' and 'b', trailing 'd', which HST (unlike Earth-based
telescopes) should be able to adequately resolve. One of the galaxy components, 'e', has yet to
have its redshift measured; HST can do this.

Question #2 Give specific details of the targets to be studied and the HST instruments and their
modes to be used. Explain how the data from the instrument/mode are required for your investigation.
Provide a table with columns as follows.

Target name/ID NGC 6027   HCG 79   EQ 1556+208   ZW VII SS Z 137 -10
UGC 10116A   Z 1557.0+2055  MCG+04- 38-0008   Seyfert's Sextet

Target Position
            Epoch 1950     Epoch 1991      Epoch 2000
R.A    15h 56m 58.5    15h 58m 48s      15h 59m 11.88s
Dec. +20d 54m 00s   +20d 47m 40.7s  +20d 45m 31s

Galactic Coordinates: 34.97 +46.88
dim: 1m 18s 1'42" ~ (2)
Magnitude: Mean Surface Brightness: +20.5
Total Blue Mag. +12.87

Vo -M(Btc) App.   Mag.     B-R      Classification
NGC 6027- 4,541   21       14.7 1.60         Sc
              a- 4,294   20.32   15.1 1.44         S0
              b- 4,446   20.89   15.3 1.27         S0
              b1- ---      ---       ---   ---          dE0
              c- 4,106   19.95   15.6                 S0
              d- 4,503   18        16.0 0.85   Sdm- Seyfert
              e-19,809  18.80   16.5 1.32         Scd (I)

Dispersional Radial Velocity- 138 km/s

Group Classification from Palomar Observatory Sky Survey is a EIII.

Instrument/Mode: FOC- f/96
Filter Median Wavelength (A) Exposures/Duration
439W 4094 1 900 sec.
F555W w/ POL 60 5416 1 900 sec.
675W 6684 1 900 sec.
791W 7906 1 900 sec
850LP 8600 1 900 sec.

These exposures will be taken of group and the incidental area around the group. Five exposures
will be used to quantify the individuals spectral classification of the group. The POL 60 filter
will be used to -

1.) observe the polarization of the area to
2.) gauge particle movement/rotation of the area quantify the age and angular momentum to
ascertain mass. This exposure will accomplish analyses similar to the intriguing polarization
study done on the Crab Nebula.

Instrument/Mode: FOC f/30 Direct Imaging (to 28th magnitude)

Filter Wheel/Hole Spectral Range (A Exposures needed
G200 2-D 1600-4000 (Red) 1/1
G450 1-C 3000-6000 (Blue) 1/1
G800 1-D 6000-10000 (UV) 1/1

  Three exposures will be centered on component 'd' and the surrounding area in the direction of
component 'a'. The exposures are used in an attempt to search for broad emission lines in order
to resolve globular clusters.
The other three exposures will be taken of the center to west edge of group component 'd' in an
attempt to resolve the starburst regions, quantify age and determine spectral classification of
the spiral.

Question #3 Given HST throughput and motion pointing constraints, show not only that the HST
can make the observation your investigations requires but that the data returned will be scientifically
useful in answering the inquiry you purpose.

The group members this study intends to investigate have magnitudes between 15-16, and the
mean surface brightness of the area is 20.5. The surrounding area is devoid of any bright
luminous objects and well within the limiting magnitude allowable. During the interval between
the months of April and August, the sun will be at opposition and this will be the safest time
to take exposures of the group. The main consideration for timing is the phase and location of
the moon, considering the low surface brightness of the group as a whole. As this group is well
away from the ecliptic, no planetary objects will approach it; Pluto at about 17 degrees away
would be the closest.
This study will require a limited amount of positioning as all members are within the field of
view of the WF/PC. Fine lock guiding should only be necessary on the parallel observation using
the FOC. The total exposure time required is 2 hrs. 45 mins., given the exposure times used to
image the cluster in 1991 by the Sulentic, Arp, Keel group.

Question #4 Explain which of the HST-unique capabilities your investigation requires and show why
your study cannot be made using a ground based telescope.

The collateral interacting features between the galaxies this study wishes to observe will need
HST's improved optics because of the relatively low surface brightness of the extended luminous
halo connecting and surrounding the group. The stringent resolution is needed to resolve
globular clusters in the 160 LY range around an extragalactic cluster at a distance of 245
million light years and will demand the penultimate observing conditions by putting maximal
demands on the guiding systems to absolutely determine that what the Hubble has resolved are
indeed globular clusters. The fact that the 'e' component has not been assigned a redshift
value, using the HST's grisms without the intervening atmospheric aberrations should remove any
controversy as to the validity of the quantity

Question #5 Outline your plans for analyzing the data you obtain and how/where you would like to
publish your results.

After the data capture phase of the project, data reduction and data analysis with assistance
of the HST imaging team, time has be offered by an engineer from Hewlett-Packard in Loveland of
a HP-720 with an upgrade of the HPUX 9.01. If a software pac exists which can batch process
.FITS into .GIF, .BMP, or other image formats for use on a IBM-compatible computer, other image
processing can be done internally.
Sky & Telescope, Astronomy, Astrophysics, and Astronomical Journal are all candidates (in order
of preference) for publishing the results of this study. As this is a program for amateur
astronomers, the best publication at this point in time is S&T: the readers to whom astronomy is
an avocation but nevertheless still a passion would have an opportunity to see the splendid
results that can be obtained by the Hubble Space Telescope II in a publication that is readily
comprehensible and available to the public.

New Considerations
Tulley-Fisher - independent method of find distance from the spiral galaxies' absolute magnitude
and it's rotational velocity. S& T August 95, pg. 16 No Anomalous Redshifts

Question #6   Supply a bibliography listing of relevant scientific publications that describe your
topic. Give the title, author, journal or book, volume number, page, and year of publication.
Supply photocopies of one to three recent articles.

Seyfert Sextet Bibliography

Arp & Bahcall: Redshift Controversy W.A. Benjamin, Inc. Advanced Book Program, Reading, Mass. P.Sci. QB 465. F
Arp, Halton: "Confrontation of Cosmological Theories w/ Observational Data", IAU Symposium #63
ed. by M.S. Longair, D. Reidel, Dordrecht, Holland (see p. 61. Summary for non velocity caused redshifts).
Barnes, Joshua, Hernquist and Scheizer: "Colliding Galaxies" Aug. 1991- Scientific American p. 40-47
Berry, Richard: Electronic Imaging of Astronomical Objects : In Press
Gordon, David and Gottesman, S.T.: "H1 Observations of Blue Compact Galaxies", The Astro. Jour'l. v 86(2) p.161-177 Feb, 1981
Halton, Arp Quasars, Redshifts & Controversies
Hickson, Paul: "Systematic Properties of Compact Groups of Galaxies", The Astro. Jour'l. v.255 p. 382-391 April 15, 19825
Keel, W.C.: 1991, PASP, 103,723
Leitherer, Claus: "Massive Stars- From the Solar Neighborhood to Starburst Galaxies", Sept. 1990- Space Telescope Science Institute Preprinted Series #467
Leitherer, Claus & Langer, Norbert: "Mass Loss & Evolution of Massive Stars in the Magellanic Clouds", Sept. 1990- Space Telescope Science Institute Preprinted Series #467
Leitherer, Claus & Lamers, Henny J.G.L.M.: "SI IV & C IV Resonance Lines as Indicators of Massive Stars in Starburst Galaxies", Dec. 1990 Space Telescope Science Institute Preprint Series #497
Malin, David and Murdin, Paul: "Colours of the Stars", Cambridge 1984 Detail on color image reconstruction and enhancement
Mihalas & Binney, Galactic Astronomy- Structures & Kinematics 2nd. ed., W. H. Freeman & Co. San Francisco 523.113 M588 1981 PV
Schweizer, Francois: "Colliding and Merging Galaxies", Science, Vol. 231, pages 227-234 January 17, 1986 Shapley, Harlow Galaxies 3rd. ed. 1972 Harvard University Press
Srendicki, Mark: Particle Physics & Cosmology: Dark Matter, U. of California- Santa Barbara 93106, North-Holland Elsiner Science Pub. B.
Sulentic, J.W. "1983 Image Processing of Connective Filament in NGC 4319", Astro. J. (letters) 265 p.
Sulentic, J.W. and Lorre, J.: "Analysis of optical imagery for Seyfert's Sextet and VV 172", Astr. Ap., 120, 36 52 1983
Sulentic, J.W. and Jean J. Lorre: "The Magic of Image Processing", Sky & Tele. May, 1984 page 407-4118
Sulentic J.W. 1987, Ap. J. 322,605
Sulentic J.W. , C.R. Rabaca, Halton Arp: First Images of a Compact Group: Seyfert's Sextet taken by HST, 12 May 1992.
Sulentic, J. W. & de Mello Rabaca, D.F. , Ap. J., June 20 1992
Sulentic, J. W. and Rabaca, C.R. 1993, in Proceedings of the HST Workshop on Groups of Galaxies, in press
Williams, B.A., McMahon, P.M., & van Gorkon, J. H. 1991, A.J. 101, 1957
Whitmore, B.C., Lucus, R.A., McElroy, D.B., Steiman-Cameron, T.Y., Sackett, P.D., & Olling, R.P.: A. J. , 100,1489
Biographical Sketch of HST Project Proposer
Name: Thomas J. Teters
Date of Birth: June
Place: Alaska
Education: College: Nebraska Western College (Associate of
Northern Arizona University (12 credits) (Astronomy T. A
Continuing education: Both personnel and institutional in computer sciences and surveying
Occupation: Land surveyor- instrument man

Brief Career Summary- After NWC I entered the construction field, polished eyeglasses, held a
sorter/operator position for Western Nebr. Computer Center. Then settled on the survey
profession in 1981 in Gillette, Wyo. where I worked for several surveying firms in varied types
of surveying which contracted with open pit coal mines, oil well locates and subdivision layout,
etc. As their boom went bust, I obtained employment with at an open pit gold mine in Hawthorne
NV and took up a position as an instrument man. In March of 1993 a reliable and busy engineering
firm, R.B.D Inc. in Ft. Collins engaged me to do topographic and subdivision surveys. In 1997 I
began working as a support Technician for an Internet Service Provider-EZLink.

Membership: Northern Colorado Astronomical Society, Longmont Astronoical Society
Front Range Astronomical SuperCluster (FRASC)
Past Membership: Nevada Astronomical Society of Reno U
Wyoming Professional Land Surveyors (Associate)
Interests: tropical fish, photography, music