Is NASA covering up Hubble pictures?
From the Hubble Space Telescope "Call for Observing Proposal"
"The telescope does not generally observe targets
within 50 degrees of the Sun [...]. When the scientific justification
is compelling, time critical observations of solar-system objects
lying between 45 and 50 degrees from the Sun may be carried out."
Keeping this limitations in mind, here is a chronology of the HST
There were also many questions about the 1 year proprietary period on
HST data. The Principal Investigator (P.I.) and his team have proposed
a project to the Space Telescope Science Institute (ST-ScI). Such a
proposal represents lots of time and efforts. If the proposal is among
the bests of all those that are received by the ST-Sci, that project
is awarded some observing time, and the PI must send a "Phase II"
proposal, which describes the observations in a VERY detailed
way. This represents a HUGE amount of work. When the observations are
finally performed, the P.I. receives the data at his institute. To
transform these raw data into nice images is time consuming. To
measure them and analyze them scientifically can take many months. The
one year proprietary period ensures that the team who has done all the
work has a privileged access to the data, but that year is very short
in comparison to the amount of work that has to be done. On the other
hand, if the data contain something spectacular, the P.I. can decide
to produce quickly some nice-looking images and release them to the
public. These are widely available, but should not be confused with
the real data, which are usually not as pretty, but scientifically
much more interesting for the astronomers (and most probably boring
for anybody else).
- Some images obtained in September and October 1995 (cf below).
- The comet was in the forbidden 50 degree region from early
November 1995 until early March 1996
- In March 1996, all the available observing time was focused on
- HST performed some observations in April, May, June, July,
observing log is available).
- The April--June images looked the same as those of fall 1995, so
there was no urgency to process/release them.
- The comet started to develop some nice jets in July 1996
- Most of the comet scientist were preparing and attending
scientific meetings in Europe during the summer.
- In response to enquiries in October (at the time of the
American Astronomical Society Division for Planetary Science
meeting), H.Weaver (P.I. of the HST program) processed some
of the latest images an put them on the
Web; they are also shown below.
- Late October 96: the comet enters again the 50deg. exclusion limit.
It will not leave it until August 1997. In March 1997, the comet
will be at 46 deg from the Sun, and therefore may theoretically be
observed. However, the second HST servicing mission is scheduled for
February 1997, and it is unlikely that the telescope will be ready
in time to observe Hale Bopp.
The above figure shows the temporal evolution of Comet Hale-Bopp over
the course of about 1 year, as observed by the Hubble Space
Telescope. In the far-left frame we caught the comet about 60 hours
after a huge outburst of dust, and the image shows an impressive
spiral structure reminiscent of a water sprinkler observed from
above. The middle frame shows the comet during a more quiescent phase
in which hardly any structure is seen in the coma without employing a
strong intensity contrast in the display. The image at the far-right
shows that the comet has now taken on a "porcupine" appearance as at
least five jets can be seen sprouting from the nucleus. The nucleus of
the comet is located at the center of each frame, but most of the
light observed is due to scattered sunlight from fine dust grains that
are emitted from the nucleus and which produce the cometary "coma".
Each frame above is 10 arcsec across. For the far-left frame this
corresponds to 47,000 km at the comet, for the middle frame this
corresponds to 49,000 km at the comet, and for the far-right frame
this corresponds to 21,000 km at the comet. (The comet was much closer
to the Earth during the September 1996 observations.)
Hale-Bopp @ IfA
Created: Thu Nov 28 16:53:34 1996 --- Updated: Sat Dec 14 21:15:00
1996 -- Hits: