Transcript No Slide Title

Rediscovery of J1842+0257 and J1812+0226
Sonny Ernst, Taylor Barber, and Brooklyn Williams
ABSTRACT
J1842+0257
While under repair, The Green Bank Telescope(GBT) in Green Bank,
WV collected more than 30 terabytes of data, producing more data
than the pulsar astronomers at the National Radio Astronomy
Observatory(NRAO), in Green Bank, could analyse. The Pulsar
Search Collaboratory (PSC), is a joint project between the National
Radio Astronomy Observatory and West Virginia University and is
funded by the National Science Foundation. The goal of this project is
to allow high school students to search for new pulsars in a effort to
help pulsar astronomers. As students of the PSC, knowing how to
correctly score and differentiate plots is vital to finding known or
unknown pulsars. In analysing numerous data sets, two already
known pulsars, J1842+0257 and J1812+0226, were confirmed and
rediscovered. Finding an already known pulsar is still very important
information and gives astronomers a more detailed picture of the
pulsar.
J1812+0226
Pulsar J1802+0257 , originally discovered in The
Parkes Multibeam Survey. The astronomers were D.R.
Lorimer, A.J. Faulkner, A.G. Lyne, R.N. Manchester,
M. Kramer, M.A. McLaughlin, G. Hobbs, A. Possenti,
I.H. Stairs, F. Camilo, M. Burgay, N.D Amico, A.
Corongiu and F. Crawford
J1812+0226 is a pulsar as exhibited in the pulsar
profile, time domain, and sub band. J 1812+0226was
first discovered by G. H. Stokes, J. H. Taylor, J.M.
Weisberg, and R.J. Dewey in 1985. The scientists
discussed the findings in A Survey for Short Period
Pulsars
BACKGROUND
In 2007, the GBT was put in stow position. This is due to the fact that
on GBT the azimuth track was being replaced. The azimuth track is
what allows the GBT to rotate. During this duration, Dr. Maura
McLaughlin, Dr. Duncan Lorimer, and SueAnn Heatherly used the
GBT to observe the sky as the Earth rotated. The GBT logged over
300 hours of data or 30 terabytes. This data was used to make the
PSC. This data is only viewed by high school students and other PSC
members. Our group is currently in the pulsar search class taught by
Mrs. Carter.
Figure 3
762.0584216 age
Spin down rate of J1812+0226
0.7939029
(
The astronomers found pulsar J1802+0257, an isolated older pulsar.
Pulsar J802+0257 has a strong signal to noise ratio, the lines in the
time domain are very prominent, as well as in the sub-band and the
DM is peaking in the right place. During it’s rediscovery, pulsar
J1802+0257 displayed something odd: It is speeding up!
An acceleration in speed implies a binary system, possible planets
orbiting the pulsar, or a glitch has occurred (a cracking of the crust on
the neutron star.)
Figure 6
. The pulsar was then analyzed for more information in 2004 by G.
Hobbs, A.G. Lyne, M. Kramer, C.E. Martin, and C. Jordan. The
new data was published in Long-term timing observations of 374
pulsars. This pulsar is slowing down commensurate with other
pulsars of the same age.
P
e
r
i
o
d
s
e
c
o
n
d
s
0.7939028
y = 1E-10x + 0.7939
0.7939027
0.7939026
Spin down rate of J1812+0226
Linear (Spin down rate of J1812+0226)
0.7939025
)
0.7939024
Image 1:GBT azimuth track repair (2007)
0.7939023
0.7939022
49500 50000 50500 51000 51500 52000 52500 53000 53500 54000 54500 55000
Figure 8 Mean Julian Date
DATA
While analysing the pulsar data, together our group found 2,008 noise
data sets, 2,986 RFI data sets, and two known pulsars.
Known Pulsars, 2,
0.04%
RFI, 2986,
59.77%
Noise
RFI
Known Pulsars
Noise, 2008,
40.19%
Figure 1
The pointings all had the same or close to the same declination. The
right ascension was almost always different. Most pointings were in
the 200 dec,-1400 and-1500
Figure 7
Figure 7 represents a plot our group found interesting. The pulse
profile shows a definite signal; as well as the time domain and the
sub-band plot. Although not very distinct, the pulses in the pulse
plot line up correspondingly in the time domain and sub-band plot.
In the Dispersion Measure(DM) plot, the peak was decent but also
broad. Knowing this, referring to the Reduced X² shows a peak over
1, meaning the signal to noise ratio is just high enough to agree with
the model and the data. This plot seemed a little too weak, but we
still believed it to be a potential candidate.
location of pointings
400
200
0
0
500
1000
1500
2000
2500
3000
-200
-400
-600
-800
Declination
(DEC) -1000
Approximation
of the Pdot
-1200
-1400
-1600
Figure 5
-1800
Right ascension
(RA)
Figure 2
ACKNOWLEDGEMENTS
J1802+0226
J1842+0257
Figure 5 shows the period derivative diagram(P-dot). a
graph of the spin down rate, magnetic field strength, or
whether or not accompanied in a binary system.
Jennifer Carter, Morehead State University, Dr. Duncan Lorimer, SueAnn
Heatherly, pulsar astronomers at the NRAO and West Virginia University,
and the National Science Foundation. And the ATNF