Pulsating Pulsars:

1
Pulsating Pulsars Adventures Outside the
Gridding Iron
Susan Booth (VAST), Nick Borowicz (Argo Community
HS, Summit, IL), Rob Culbertson (Langley HS,
McLean, VA), Dottie Edwards (Strasburg HS,
Strasburg, VA), Russ Kohrs (Broadway HS,
Broadway, VA), Duncan Lorimer (WVU), Steve Rapp
(Linwood Holton Governors School, Abingdon, VA)
Abstract Fifteen pointings, each containing
plots of data were analyzed. The purpose of this
analysis was to examine data collected during
several Green Bank Telescope (GBT) 350MHz drift
scan surveys. Three prepfold plots indicated the
presence of two known pulsars (J1643-1224 and
J1744-1134) and one potential candidate pulsar.
It was later determined that this candidate
pulsar was recently validated and is now known as
J1853-0649. The data from this 820MHz survey
confirmed the presence of J1643-1224. The
observation of J1744-1134 suggested (based on
period and DM) that the follow up observation
actually detected a possible separate radio
source. For J1853-0649, the data collected
displayed a large amount of RFI with a very faint
pulsar signature which when refolded confirmed
the presence of the pulsar at that location.
Thus, gridding at that location may have provided
more data from that pointing and reduced the need
to refold the data.
Conclusion Pulsar
astronomy is often a tedious and frustrating
activity. Of the fifteen pointings 1.6 of the
survey data contained known or candidate pulsars,
36.2 of the plots contained RFI, 63.8 contained
unintelligible noise. Gridding of pulsars
J1853-0649 and J1744-1134 at 820MHz may lead to a
better understanding of these regions.
Astronomical Setting
The narrower beam width of the 820MHz receiver
requires gridding in order to cover the same
beam area as the 350MHz receiver.
Above The locations in the night sky of the 3
pulsars that were observed using the Green Bank
Telescope on July 21, 2011 Below The locations
of the same 3 pulsars in Milky Way Galaxy.
Team Hulse hard at work slewing the telescope and
collecting data.

• Method
• A random assortment of fifteen pointings, twelve
  previously viewed and three unanalyzed, were
  examined by a team of six Pulsar Search
  Collaboratory (PSC) members.
• Plots within these pointings containing RFI or
  noise were eliminated and plots indicating the
  potential presence of a pulsar were selected for
  follow up observations.
• Follow up observations of two known pulsars and
  one candidate pulsar at 820MHz were conducted
  using the Green Bank Telescope.

Results and Discussion The data collected on
J1643-1224 revalidated the presence of that
pulsar. Given a negligible Pdot in the survey
plot and the knowledge that this pulsar is part
of a binary system, the observed spin down rate
of 1.1x10-16 can be attributed to Doppler
variations in straight line velocity (Lorimer,
personal communication). The follow up
observation of J1744-1134 appears to be of a
different radio source. Period and DM
differences between the survey and follow up
observations were each on the scale of 2 orders
of magnitude. There was also an observed
difference in the period. After refolding the
data collected on J1853-0649 the presence of this
pulsar was revalidated. The source of the RFI in
the original observation is still unexplained.

• Extensions/Further Research
• Validation of the presence of two pulsars in the
  vicinity of J1744-1134
• Gridding of J1854-0649 in order to investigate
  the possible presence of one or more pulsars in
  that location
• More detailed observations of J1643-1224 in order
  to better characterize this binary pulsar system

The plot below shows the same data, folded
differently, using a different period.
Acknowledgements Special thanks to the National
Radio Astronomy Observatory in Green Bank, WV.
Data on pulsar J1843-0649 indicating the presence
of large amounts of RFI. The pulsar signal can
be seen faintly in the Time/Phase plot as a
diagonal signal.