1. Spectroscopy with TianMa 65m and also FAST
Junzhi Wang
SHAO
On behalf of the Shanghai 65m RT Team

2. Outline Introduction of TianMa telescope
Capability of radio spectroscopy with TianMa
Our ongoing observational projects with TianMa
Spectroscopy with FAST early science

3. Shanghai 65m Radio Telescope
65-m in diameter, fully steerable radio telescope
Active surface system installed
Covering 1 – 50 GHz with 8 bands
L(1.6GHz), S/X(2.3/8.4GHz)
C(5GHz), Ku(15GHz), K(22GHz)
Ka(30GHz), Q(43GHz)
General-purpose (radio astronomy,
single-dish, VLBI, geodynamics)
Funding Agencies:
Chinese Academy of Sciences (CAS)
Shanghai Municipality
Chinese Lunar Exploration Project
Cost ≈ 32M USD

4. Project Timeline
2008：funded; contract to CETC54 for the antenna construction
2009: complete design (international review panel); start manufacturing; foundation laying ceremony on December 29
: site construction started on March 19, 2010; foundation completed; antenna construction (wheel-on-track, BUS, alidade, panels, …); active surface system (contract, design, fabrication, installation of actuators)
: L/S/X and C band Rxs in place; first light on October 26, 2012 & inauguration 2 days later; start commissioning; got named (天马); participation in the Chinese Lunar Mission (ChangE); DIBAS installed & tested
: on-site system testing; science observations at L/S/C/X bands; active surface tested; Ku/K/Ka/Q band commissioning; project accomplished

5. Telescope Specs Frequency coverage: 1 ~ 50 GHz
Primary reflector adjustable with 1104 actuators
Surface accuracy (nominal)：
0.53mm RMS (without active surface)
0.29mm RMS (with active surface)
Aperture Efficiency：
L/S/C > 60%, X > 55%, Ku > 40%, K > 20%
Ka > 50%, Q > 45% (with active surface)
Pointing accuracy：
6 arcsec (wind < 4m/s) [c.f. beam ~ 22 GHz]
10 arcsec (wind < 10m/s)
30 arcsec (wind < 20m/s)
Elevation limits: 5~90 degree
Slew rates: 0.5 degree/s (azimuth), 0.3 degree/s (elevation) 5

6. Receiver specs Band "L" "S" "C" "X" "Ku" "K" "Ka" "Q" Wavelength (cm)
21/18 13
6/5
3.6
2/2.5
1.3
0.9
0.7
Freq range (GHz)
4-8
12-18
30-34
35-50
Freq low (GHz)
1.25
2.2 4
8.2 12 18 30 35
Freq high (GHz)
1.75
2.4 8 9
26.5 34 50
BW (GHz)
0.5
0.2
0.8 6
8.5 15
BW/CF (%) 33 67 40 38
Freq high/low
1.4
1.1
2.0
1.5
(")
647.4
422.2
161.8
112.9
64.7
43.6
30.3
22.8
T(Sky) (K) 10 25 26
T(Rx) (K) 14 21 22
T(Sys) (K) 32 27 60 43 66
Efficiency
55%
60%
50%
DPFU (K/Jy)
0.66
0.72
0.60
SEFD (Jy) 39 46 48 41
100 72
110
Sensitivity (mJy)
128MHz BW/10min
0.142
0.165
0.110
0.175
0.147
0.360
0.258
0.396
full BW/10min
0.072
0.132
0.020
0.070
0.022
0.044
0.046
0.037
Feed Type
Compact
Conical
Polarization
Lin & Circ
Dual Circ
Refrigerator
1020
350
Structure
Single Pixel
Dual Band
Dual Pixels
Status
Installed May 2013
Installed Dec 2012
Installed Sep 2014
Installed Mar 2016
Installed Dec 2014

7. DIBAS: DIgital BAckend System
An updated version of the NRAO-VEGAS (Versatile GBT Astronomical Spectrometer), customized with the addition of NRAO-GUPPI (Green Bank Ultimate Pulsar Processing Instrument)
Support two types of observing modes
Spectral line modes: support 29 modes, including wideband up to 16,384 channels, narrowband up to 524,288 channels and, sub-band modes (higher spectral-resolution over multiple narrow bands (sub-bands) within the sampled bandwidth)
Pulsar modes: support the incoherent/coherent search and pulsar timing modes. 7

8. DIBAS Spectrometer Specs8

9. DIBAS Spectrometer Specs

10. DIBAS Spectrometer Specs(cont’d)

11. K-band specifications
Requirement
Frequency Band
GHz (complete K-Band coverage)
TRX (each beam, not including sky)
< 25 K (75% of band), < 36 K (entire band)
Number of beams
2 (expandable up to 3)
Polarization
dual, circular (axial ratio <= 1 dB)
Polarization Isolation
>25 dB
Pixel-Pixel Isolation
>30 dB
Aperture Efficiency
>55%, any pixel
Sideband (image) rejection
> 25 dB
1st fixed Local Oscillator frequency
16 GHz
Instantaneous RF Bandwidth
8.5 GHz ( GHz)
Headroom
> 30 dB (to 1 dB compression point) 11

12. EAVWS2010, Kagoshima, Japan, 22-24 April 2010
RFI Environment
Two site surveys (2008 May and 2009 October) are consistent in that，most RFIs appear at the outside of the designed bands, and at C-band and above RFI is not a problem. Some RFIs at L-band!!!
L 1.25~1.75GHz
S 2.15~2.45GHz
C 4.5~7GHz
X 8~9GHz
EAVWS2010, Kagoshima, Japan, April 2010 12

13. SH65m site

14. RFI protection

15. site meteorology - PWV Precipitable Water Vapor (PWV)
Good in Autumn/winter !

16. site meteorology - optical depth (τ)
22GHz： about 1/3 days with less than 0.1 optical depth
43GHz： about 1/4days with less than 0.1 optical depth

17. Capability of Spectral line
high sensitivity, wide frequency coverage
Suitable for spectral line observations.
Standard PS mode and OTF mode can be used now.
Data from 2IFs (~1GHz) obtained Simultaneously
Discovery of new lines (masers or thermal)
Search for some important line emissions, such as high-z CO (bw=4MHz, T=20hr, sigma=0.2 or, 43 GHz)
Multiple-line observation towards SFRs
Deep K-band Galactic Plane Survey 17

18. Spectral line emission in ~10 - 50 GHzK 18

19. Molecular lines at cm-band
Menten 2004 19

20. C-band（4-8 GHz）
> 1K：6.7 GHz CH3OH，4.765 & GHz OH maser, CH2CNH (-1.3 K, Sgr B2, Lovas et al. 2006, no follow-up)
>0.1K：H2CO absorption，NH2CHO
(0.3 K, Sgr B2, Rub et al. 1971)
> 0.01 K: HC5N, HC7N, HC9N…
RRLs
Ku ( GHz) band is another important band for TianMa 20

21. NSFC Major project Studying Star formation and ISM with TianMa
Chief Scientist : Prof. Zhiqiang Shen
From 2016Jan to 2020Dec
Group 1: Star formation in the Milky Way
Group 2: ISM properties and star formation history in the Milky Way
Group 3: Dense gas and Star formation in nearby galaxies
Group 4: Mega-masers, starburst and AGN 21

22. Group 1:Star formation in the Milky Way
6.7 GHz CH3OH maser survey toward candidates of massive star forming regions selected with WISE color (on-going, almost done)
RRL survey toward massive star forming regions selected both with WISE YSO candidates and strong radio continuum emission (on-going)
NH3 mapping observations toward massive star forming regions based on CH3OH and RRL survey (will start from the end of this year)
Further high resolution observational studies with (sub-)millimeter observations for some of the sources 22

23. Work Progress

24. Group 2:ISM and Star formation history in the Milky Way
Observing lines of long carbon chain molecules, such as HC5N, HC7N in Galactic molecular clouds
Determining electron properties (density, temperatures, etc.) with the observations of multiple transition RRLs
Isotopic abundances of 12C/13C, 14N/15N, 33S/34S with different distances to the Galactic center (DGC): star formation history? 24

25. HC5N, HC7N, HC9N,C3S, C6H, C8H and isotopic line of HC3N were detected
Lines of long carbon chain molecules in Serpens South 1a detected with TianMa
Left：HC3N 2-1 and its 13C isotopic lines; Right: Comparison between Serpens South 1a and TMC-1、Lupus-1A。
HC5N, HC7N, HC9N,C3S, C6H, C8H and isotopic line of HC3N were detected
Li, Juan et al., , 2016, ApJ, 824, 136
“TMRT Observation of carbon-chain Molecules in Serpens South 1A”
as the first refereed paper of spectroscopy observation with TianMa

26. Li Juan et al. in preparation

27. Group 3:Dense gas and star formation in nearby galaxies
Dense gas tracers and star formation law: what can we do with TianMa? CS 1-0, HC3N 5-4 & 2-1 in nearby galaxies with TianMa
Optically thin lines of dense gas tracers in galaxies: isotopic lines, such as 13CS 1-0 and C34S 1-0
Mapping massive star forming regions with the same lines as that for galaxies: obtain the conversion factor of luminosity to dense gas mass 27

28. Detected dense gas tracers
Nearby galaxy M66 HC3N 2-1
Will test CS 1-0 in coming months using Q band receiver 28

29. Group 4:Mega-maser, starburst and AGN
Searching for new H2O mega-maser sources
Searching for CH3OH mega-masers
Radio continuum properties of H2O and OH mega-maser host galaxies
VLBI imaging for H2O and OH mega-masers 29

30. Five-hundred-metre Aperture Spherical Telescope (FAST)
Diameter: 500m
Frequency range:70MHz-3GHz, early science (270MHz-1620MHz)
Pulsar, spectroscopy, VLBI
2016 Sep 25 30

31. Spectroscopy with FAST early science
Capabilities: limited tracking time
flux calibration is not perfect
weak RFI is not well known
bandpass stability is not perfect
Good sensitivity
Better choices: Known frequency and red-shift, relatively strong, but still weak lines
hard for long integration time
difficult for unknown frequency lines
Largest OH MM sample
highest red-shifted OH MM (?)
OH mega-maser survey
Long carbon chain lines (HC2n+1N)
in low mass star forming regions
Largest molecule (?) 31

32. Thanks for your attention !