[Lofarpwg] LOFAR LBA census draft -- ready for commenting

Fri Aug 23 15:11:34 UTC 2019

Hi Anya,

Find below some comments as requested. Most comments are pretty small, 
so that is great! I will make some maybe slightly more controversial 
point first. The rest of the comments you can find below this email.

Figure 2: I don't think having the dynamic spectra adds a lot, so I 
would remove them. In addition I had a question about the cleaned freq 
vs phase plots: why are there white rows which do not appear in the 
uncleaned version? Rows with empty samples appear as orange for other rows.

Figure 3: I don't really see the point in showing for each pulsar & beam 
what fraction of the data was deleted. I think that if this information 
should be available to the reader, then it should be in a table in the 
appendix. At the moment the figures in the paper itself (excluding the 
appendix) is dominated by plots which show that the data is non-ideal 
(two large figures about dropped packets & RFI, two small figures about 
interesting stuff related to the sample). If you want to show something 
related to the zapped fraction, I would make a histogram of the fraction 
of useful data, which is much smaller. I also don't think there is a 
reason to keep the inset. As you already do, you can simply state in the 
text that there is no correlation with date. Making the plot was a 
useful diagnostic for us, but the information in the inset will not be 
particularly useful for the reader.

Section 4: I think this is part of "Observations and data reduction", so 
I would make it a subsection of section 3.

It would be great to have this published!

Cheers,
Patrick

Abstract - remove "Despite some telescope malfunction". I think it only 
puts off readers from reading the paper, and it is not particularly 
useful for the reader to read at this point.

Section 2: 2nd paragraph - Add a sentence at the end like "The 
consequence is that only 88 out of the 194 pulsars which are in the HBA 
census were observed and discussed here." At the moment the text doesn't 
quite explicitly states if only HBA pulsars were observed, or all 
pulsars HBA pointings are available for (without the pulsar necessarily 
being detected).

3rd paragraph:

with AN incoherent dedispersion scheme.

only compensated FOR between channels

The proposed source sample therefore ONLY? included pulsars with 
sufficiently (if only is not missing from the sentence, then I don't get 
the point of the paragraph)

without ephemerides updateS.

hoping to DETECT strong single pulses.

Last paragraph of section 2: At the moment it just says "here is a plot" 
without a conclusion attached to it. I think it is there to back up the 
last statement from the previous paragraph. So I would delete the last 
paragraph and simply write: "with some preference for closer/brighter 
sources (SEE FIG. 1)."

Caption Fig. 1: I would remove "(see text for more information)", since 
the text kind of says this is done in an, at least for the reader, 
undefined way. Also, "THE scattering time was estimated with THE Galactic"

Footnote 2: Either in THE original ATNF (and end the sentence with a .)

Section 3:

"(beam 0 on the NOMINAL POSITION OF THE TARGET"

"private sources" - clarify these is Lovell and GBT positions.

observations at the Jodrell, Lovell -> observations with the Lovell 
telescope at Jodrell Bank

in many cases the initial DM -> in many cases the DM as derived from 
higher-frequency observations

“old” -> these incorrect

of THE relative signal strength difference

"for each time/frequency data cell in phase-integrated dynamic spectrum" 
- I'm not 100% sure what this means, so please clarify. Phase-integrated 
means integrated over pulse longitude? So that means you get 300 (nr 
freq channels) numbers per 5 second subint?

Caption Fig. 2: An example of diagnostic plots without (left) and with 
(right) dropped packed cleaning APPLIED for one observation of THE 
bright pulsar B0809+74. The upper row of plots shows the statistic of 
THE two polarizations, the lower PLOTS SHOW THE dynamic and folded 
spectra, waterfall diagram, and the average profile.

Figure 2: The plots should have tick marks. The horizontal labelling of 
the top plots is confusing. There are four pannels. The upper three have 
(I assume) a horizontal axis corresponding to frequency (as shown at the 
top). Only the lower panel has dP as the horizontal axis. However, for 
the middle two plots this is not clear from the figure. Having tickmarks 
in all panels would help. Possibly reducing the gap to zero for the 
first 3 panels would also clarify they share the same horizontal axis, 
but the lower panel not.

For a few pulsars (namely,
B0105+68, B0643+80, B0656+14), the data was contaminated
to the point where no cleaning (manual or automatic) could help.
Thus, we exclude these pulsars from our sample.
->
For only 3 pulsars (namely, B0105+68, B0643+80, B0656+14), the RFI 
prevented useful analysis, hence they were exclude from our sample.

"Overall, the fraction of band that has been deleted due to dropped 
packages or RFIs is quite substantial" - I fully agree with Joeri's 
suggestion related to this paragraph.

Section 3.1

We adjusted pulsar period P and DM with the PSRCHIVE pro-
gram pdmp, maximizing integrated S/N of the frequency- and
time-averaged profile over the set of trial values of P and DM.
->
We adjusted THE FOLD PERIOD AND THE INTRA-CHANNEL DISPERSION DELAY (i.e. 
adjusting the pulse period would involve sending a missile to the 
pulsar!) with the PSRCHIVE program pdmp, maximizing (remove integrated) 
THE S/N of the frequency and time-averaged profile. REMOVE REST OF SENTENCE

initial number of PHASE bins

Caption figure 3:
Pulsars are ordered by the maximum deleted fraction.
->
Pulsars are ordered by the highest deleted fraction of the beams.

Same caption: Delete "Pulsars B0656+14, B0105+68, and B0643+80,
were excluded from the analysis due to unmanagable RFI contamina-
tion." -> Already said in text, so no need to repeat this, especially 
given the text is quite negative.

Back to section 3.1:

thus for brighter pulsars THE DM may have A BIAS depending on the 
assumed profile evolution.

About the same sentence: you quote the pdmp DM's right? In that case the 
"assumed profile evolution" is that there is no profile evolution. It 
would be good to clarify this.

Fig. 4 shows THE CORRELATION BETWEEN DM and the estimated scattering 
time over period for the detected and non-detected pulsars.

Section 3.2 - I agree with Joeri this should not be part of 
"Observations and data reduction"

Section 4:

Folded data files were calibrated
->
The folded data were calibrated

A coherence factor of 0.85 was used: is there a ref for the 0.85?

The off-pulse windows
->
The on and off-pulse windows (surely you need the on-pulse window as 
well as the off pulse window).

Judging from the relatively well-measured spectra (e.g.
PSRs B0809+74, B1133+16, B1508+55, and others), the LBA
measurements stay within the spread of literature points, which
is by a factor of few.
->
For those pulsars for which multiple spectra have been published (e.g.
PSRs B0809+74, B1133+16, B1508+55, and others), the LBA measurements are 
consistent with the reported fluxes, which vary by a factor of a few.

adopting adopted -> adopting

THE total flux density error

Interestingly, 19 out of 44 detected pulsars WERE DETECTED WITH THE 
HIGHEST S/N IN A side beam

TEC (like DM) should not be in italics in equation 1 and the text.

5.1

combined with the literature measurements
->
combined with published measurements (i.e. not a measure of literature, 
which might be so many kg of A&A papers per year).

PL is undefined

5.2 - It would be great if the suggestions of Michael and Joeri could be 
used to beef up this a bit, which would also help the conclusion section 
and the abstract.

That's it! Great work!

On 16/08/19 07:53, Anna Bilous wrote:
> Dear all,
>
> please find attached the draft of LBA census. Please let us (myself,
> Louis, JM & Vlad) know if you have any comments on it. We would like
> to submit it on Aug 30 due to Louis'es graduation constraints. Sorry
> for the quite short notice, but the paper is short and very simple, so
> it should not take long to read it.
>
> Cheers,
> Anya
>
>
> _______________________________________________
> lofarpwg mailing list
> lofarpwg at astron.nl
> http://mailman.astron.nl/listinfo/lofarpwg

-- 
Dr. Patrick Weltevrede, senior lecturer in pulsar astrophysics
Jodrell Bank Centre for Astrophysics,
School of Physics and Astronomy, University of Manchester

Office 3.210 Alan Turing Building
Tel: +44 (0) 16127 54162
Website: http://www.jodrellbank.manchester.ac.uk/

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