D3A Test Plan
Types of Tests
Tentative Test Plan
1. Setup
Initial pointing of dishes should be at declination of Cyg A (Declination:+40.7°, Zenith Angle: -8.6°). This is the brightest available source transiting at night this time of year. It is also bright enough to see with just the two dishes, without the Galt. The absolute pointing can be within +/-0.2°, but the relative pointing of the two dishes should be within 1-2 arcmin. CHIME/HIRAX-like clover leaf feeds installed first.
2. Nuts and Bolts
Turn everything on. Collect raw ADC data for each input. Look at some histograms to verify we are exercising the correct number of bits (i.e. RMS level). Adjust attenuators as necessary. Also look at spectra (Example CHIME plot below). This can be done during the day. Expected duration: 1-2 days.
3. Sanity Checks
Collect full correlation matrix data for a solar day. Look at autocorrelation power as a function of time/RA and frequency. Do we see the sky? Do we see Cyg A? Fit for primary beam FWHM, amplitude, and centroid. Compare autocorrelations of two dishes. What are the differences? Get calibration in Janskys as a function of frequency. Look for frequency ripple/systematics in calibration. Get noise estimates in both Jy and T as a function of frequency. Do we see expected fringing between two dishes in cross correlation? Fringestop to location of Cyg A. Expected duration: 3-5 days of data taking, possibly more of analysis.
4. Detailed Characterization
Assuming Galt is back online, do beam cuts, coordinating with CHIME to observe shared accessible point sources. This will require occassional repointing of the dishes. If Galt is not available, swap in wideband feeds and repeat tests 1-3.
Other Possible Tests
Observatory location
Geographical coordinates: 49°19′15″N, 119°37′15″W (49.320751°, -119.620811°)
Elevation: 546 m
Source Sensitivity
The calculations producing the plot below assume that the total antenna temperature of both telescopes (the 3m and the 26m) is dominated by the system temperature. While this is basically always true for a 3m dish, this is not true for the 26m for sources >25Jy. For these bright sources, the plot below underestimates the required integration time. However, since the required integration time for a SNR of 1000 is <<1s even for a 25Jy source, one can conservatively conclude that it is no worse for brighter sources.
Furthermore, it should be noted that this is the integration time required to map out the central region of the main lobe. More generally, the integration time is inversely proportional to the gain of the 3m dish. Therefore, if the side lobes are 20dB below the main lobe, for example, the required integration time to map the side lobes is 100x longer for the same source flux.
See attached Python notebook for calculation details.
| DEC |
Zenith angle |
arcmin/sec |
sec/arcmin |
| +79.32° |
+30° |
0.046 |
21.58 |
| +69.32° |
+20° |
0.088 |
11.32 |
| +59.32° |
+10° |
0.128 |
7.84 |
| +49.32° |
0° |
0.163 |
6.14 |
| +39.32° |
-10° |
0.193 |
5.17 |
| +29.32° |
-20° |
0.218 |
4.59 |
| +19.32° |
-30° |
0.236 |
4.24 |
Test sources
Bright Sources
Here is a list of bright point sources from Berger et al., 2016
| Source |
RA |
DEC |
Zenith angle |
S(ν = 681 MHz) |
| Cassiopeia A |
350.85° |
+58.82° |
+9.49° |
4670 ± 154 |
| Cygnus A |
299.88° |
+40.73° |
-8.59° |
3216 ± 68 |
| Taurus A |
83.62° |
+22.03° |
-27.29° |
1108.0 ± 0.71 |
| Virgo A |
187.71° |
+12.39° |
-36.93° |
399 ± 20 |
| Hercules A |
252.80° |
+4.99° |
-44.33° |
105.8 ± 2.2 |
| Hydra A |
139.52° |
-12.09° |
-61.41° |
87.2 ± 1.4 |
| Perseus B |
69.27° |
+29.67° |
-19.65° |
78.7 ± 1.5 |
| 3C 295 |
212.84° |
+52.20° |
+2.88° |
38.8 ± 0.4 |
Note: zenith angle is the difference between the source declination and the observatory latitude. At transit, positive zenith angles are north of the zenith and negative angles are south of the zenith. Sources greater than 30° from zenith are in red.
Pulsars
Here is a list of pulsars greater than 100 mJy within 30° of zenith (source: http://www.atnf.csiro.au/research/pulsar/psrcat/)
MichaelRupen asks: Am I right in assuming the flux density here is averaged over all pulse phases, rather than gated? And further correct in believing these are averages over a large number of pulse periods?
| Source |
RA |
Dec |
Zenith Angle |
S (ν = 400 MHz) |
Period (s) |
Pulse FWHM (ms) |
Duty Cycle (%) |
| B0329+54 |
53.25° |
+54.58° |
+5.26° |
1.5 ± 0.2 |
0.715 |
6.6 |
0.92 |
| B0531+21 |
83.63° |
+22.01° |
-27.31° |
0.55 ± 0.10 |
0.033 |
3.0 |
9.09 |
| J0341+5711 |
55.25° |
+57.18° |
+7.86° |
0.365 |
1.888 |
- |
- |
| B2016+28 |
304.52° |
+28.67° |
-20.65° |
0.314 ± 0.030 |
0.558 |
14.9 |
2.67 |
| B1937+21 |
294.91° |
+21.58° |
-27.74° |
0.240 |
0.0016 |
0.0382 |
2.38 |
| B2111+46 |
318.35° |
+46.74° |
-2.58° |
0.230 ± 0.011 |
1.015 |
32.1 |
3.16 |
| B1946+35 |
297.10° |
+35.67° |
-13.65° |
0.145 ± 0.009 |
0.717 |
19.3 |
2.69 |
| B1508+55 |
227.36° |
+55.53° |
+6.21° |
0.114 ± 0.005 |
0.740 |
10.9 |
1.47 |
| J2238+6021 |
339.50° |
+60.35° |
+11.03° |
0.1111 |
3.07 |
- |
- |
| B2217+47 |
334.95° |
+47.91° |
-1.41° |
0.111 ± 0.012 |
0.538 |
7.5 |
1.39 |
| B1237+25 |
189.92° |
+24.90° |
-24.42° |
0.110 ± 0.033 |
1.382 |
44.5 |
3.22 |
| B2154+40 |
329.26° |
+40.30° |
-9.02° |
0.105 ± 0.007 |
1.525 |
38.6 |
2.53 |