Yingxi Zuo, Ji Yang Purple Mountain Observatory, CAS Sino-German workshop on radioastronomy Sep 13, 2005 Urumqi Delingha 13.7-m mm-Wave Telescope

OUTLINE Site Overview Telescope Description Technical Upgrade Activities Future Plans Science Activities

Site Overview -- General Information Location: – 35km from Delingha City, Qinghai, China Longitude: 97  33.6E Latitude: 37  22.4N Altitude: 3200 m Dry & Cold in Winter Delinha Nanjing

Site Overview -- Atmospheric f LO =112.6 GHz

Telescope Description – System Block Diagram Be able to observe CO(1-0) and its isotopes simultaneously

Telescope Description -- Current Status (1) Antenna Performance – Enclosed in a High-Transparency Radome (85-90%) – Diameter: 13.7 m – Pointing Accuracy: < 10” over the whole sky – Beamwidth (HPBW): ~60” – Aperture Efficiency: 39% – Main Beam Efficiency: 77% – Surface Accuracy: ~0.1 mm

Telescope Description -- Current Status (2) Receiver – 85 to 115 GHz SIS Receiver – T SYS : typically ranging from 180 to 250K Backends – Continuum backends (Bandwidth 800MHz) Total Power (TP) Chopping Modulation (SP) – Spectrum Backends AOS1: Center 70MHz / BW 43MHz / 1024 chs AOS2: Center 70MHz / BW 43MHz / 1024 chs AOS3: Center 225MHz / BW 145MHz / 1024 chs Observation Mode – Position-Switch, spectral mapping – 12 CO (J=1-0), 13 CO (J=1-0), C 18 O (J=1-0) observation simultaneously – Fast beam switching (chopper-wheel modulating), continuum mapping

Upgrade Activities (1) -- Multi-Line System (2002) Observing 12 CO, 13 CO, C 18 O (J=1-0) lines simultaneously, Because of the DSB Receiver GHz ⇓ AOS GHz ⇓ AOS GHz ⇓ AOS3 Set to GHz

Upgrade Activities (1) -- Multi-Line System An example of simultaneously observations of CO(J=1-0) and its isotopes, toward NGC The on-source integration time is 60 seconds and T sys =248K.

Upgrade Activities (2) -- SIS Mixer Stability Improvement Below 100 GHz (2004) The SIS mixer is designed to operate in the range of GHz, but … Below 100 GHz, the pumped quantum steps are too flat to stably bias (very large dynamic resistance at the step) DC bias is very sensitive to noise and interference Solution: putting a shunt resistance in the DC bias circuit of the mixer, parallel to the SIS junction. Reducing the dynamic resistance Pumped I-V Without any shunt resistance in the DC bias circuit Pumped I-V with a 36  resistance paralleled to the SIS junction

Upgrade Activities (2) -- SIS Mixer Stability Improvement Below 100 GHz (2004) After putting a shunt resistance, the stability improved significantly, in the range of GHz (f LO ). See the red points. The black points indicate the case before (without any shunt resistance).

Upgrade Activities (2) -- SIS Mixer Stability Improvement Below 100 GHz (2004) Five-point mapping toward an SiO(J=2-1) maser source at GHz, to verify telescope pointing on the northern sky Source: R-CAS Line:SiO ( =1, J=2-1) It is possible to take five- point mapping observations toward SiO maser sources at GHz to verify the telescope pointing on the northern hemisphere

Upgrade Activities (3) -- Near Field Receiver Beam Measurement System (2004) Measuring the receiver (including all the optical components) beam pattern to determine – Whether all the optical components are well aligned or not – Receiver beam axis (other than the mechanical axis) – Antenna illumination, edge taper

Upgrade Activities (3) -- Near Field Receiver Beam Measurement System (2004) A probe source is mounted on an x-y motion stage Probe scanning area: 500×500 mm The scanning measurement should be taken at (at least) two different distances from the receiver to determine the beam axis. Then using a laser beam memorizes the axis for further aligning the receiver with the sub-reflector. Scalar measurement, only measured the power, the phase information may included in the future

Upgrade Activities (3) -- Near Field Receiver Beam Measurement System (2004) x y The red circle indicates the sub-reflector edge. The edge taper is about –10dB

Upgrade Activities (4) -- Subreflector Real-Time Control (2004) The subreflector is relatively large (1.08m) and heavy It will tilt and drop down a bit with EL getting low due to gravity, affecting the alignment (between subref. and Rx, and between subref. and main dish) This can be corrected by re-positioning the subref. – Re-position Z1 axis and Y axis simultaneously while EL changes

Upgrade Activities (4) -- Subreflector Real-Time Control (2004) Measured 2-D beam pattern EL=71° Saturn map EL=35° Jupiter map

Future Plans Antenna servo system updating Digital Spectrometer with 500MHz BW Joining east-Asia mm-wave VLBI network

Science Activities Physical structure study of Galactic molecular clouds High-velocity outflows from young stellar objects Interstellar chemistry Molecular gas distributions in the Galactic star form regions Galactic dynamics Star evolution and molecular gas of late stars Large-scale molecular line survey for cold IRAS sources in the Galaxy ……

Recent Selected Publication (I) -- Molecular Clouds & Star form Regions Ao, Yiping; Yang, Ji; Sunada, Kazuyoshi, 13CO, C18O, and CS Observations toward Massive Dense Cores, AJ, A, 2004 Qin S.L., Wu Y.F., et al, Star Formation in Molecular Cloud Associated with IRAS ， 2004 ， Chinese Physics Letter ， Vol.21 No.8, 1677 J. Sun, et al., A study of molecular clouds with compact HII regions in Galactic Science in China (A), 2001 Y. Xu, D. Jiang, X. Zheng, M. Gu, Z. Yu, C. Pei High-Velocity H2O Maser Associated Massive Star Formation Regions Chin. Phys. Lett., 18(12), (2001) J. Sun, Y. C. Sun, New detected CO(J=1-0) emission from planetary nebulae Science in China (Series A), 43(2), 217, (2001) Y. Wu, J. WU, and J. Wang, A search for massive dense cores with 13 CO J=1-0 line A&A, 2001, December 12

Recent Selected Publication (II) -- Molecular Outflow Xu Y., Yang J., Zheng X.W., et al, Discovery of Multiple outflows in IRAS , 2004 ， Chin. Phys. Lett., Vol.21, No.10, SUN K.F., WU Y.F., A New High-velocity Molecular Outflow of IRADS ， 2003 ， Chinese Astronomy and Astrophysics ， 27, Y. Xu, D. R. Jiang, C. Y. Yang et al., High-velocity gas associated ultra-compact HII regions. Science in China(A), 32, , 2002 S. Qin, Y. Wu New high-velocity bipolar outflows in S39 and IRAS Science in China (Series A), 2001 Y. Wu, C. Yang, Y. Li, et al. High-velocity molecular outflows near massive young stellar objects Science in China (Series A), 42(7), 732, (1999)

Recent Selected Publication (III) -- Survey of Molecular Lines from IRAS Sources J. Yang, Z. Jiang, M. Wang, B. Ju, & H. Wang A Large-Scale Molecular Line Survey for Cold IRAS Sources in the Galaxy: I. The CO (J=1-0) Data ApJS, v141,157, (2002). J. Yang, Z. Jiang, M. Wang, H. Wang, R. Mao, B. Ju, &Y. Ao Molecular Line Studies of Galactic Young Stellar Objects APRM2002_OHP (invited talk) ， Japan, 2002 Ji Yang Galactic Star Forming Regions: Local and Distant in Proceedings of 3rd OCPA3(invited talk) ， 2000

Recent Selected Publications (IV) – Other Topics Wu Y.F. ， Wang J.Z. ， Wu J.W., A Search for Extremely Young Stellar Objects ， 2003 ， Chin. Phys. Lett. ， Vol.20, No.8, 1409 Y. Xu, X. Zheng, D. Jiang, et al, An H2O flare in GGD25, Chinese Science Bulletin, 46(1), (2001) J.J. Zhou and X.W. Zheng, Short Time Variability of the Water Masers in W51M, Astrophysics and Space Science, 275, (2001) Y. Xu, X. W. Zheng, et al, Rapid time variation of water maser emission in W3(OH) and NGC6334C, Astronomy and Astrophysics, 364 （ 2000 ）， 232. Y. Wu, Wang, Wu, Yan, Lei, Sun, Wang, A 13CO mapping study for massive molecular cloud cores, Science in China (A), 44(4), (2001) C. C. Pei, R. Q. Mao, Q. Zeng, Molecular lines and continuum from W51A, Science in China (A), 44(9), (2001) Y. Wu ， H. Yan ， J. Wu ， Y. Zhao, A mapping study for massive dense cores, Imaging at radio through sub-millimeter wavelengths, ASP Conference Series, 217(2000),96.

Sample Spectral Lines Obtained from the 13.7-m Telescope Besides CO, 13 CO and C 18 O, the telescope can be used to observe many other molecular lines in the 3mm band, such as HCO+, N2H+, CN, CS, CH 3 CN, SO, HC 3 N, CH 3 OH, OCS, SiO, HCN, CH 13 CN, …, from molecular clouds and circumstellar envelope. Following are some examples of molecular transition spectra obtained from our telescope.

HC 3 N Line Toward IRC+10216

CH 3 OH Line Toward Orion

CN Hyperfine Transitions Toward Orion

N2H+ Lines Toward L134N

HCO+(1-0) Line Toward S140

H13CN (1-0) Line Toward OrionA

Welcome to Delingha Open Time: September 1 – May 31 Proposal submission (all over the year)