45m > Proposal Information > Status Report for Open Use Observations

Last Update: 27^th June 2023

Status Report for Charged Telescope Time 2024--2025

• System Overview

• Antenna
• Frontends
• Backend
• Distribution of IFs to Backends

• Observing Modes
• Intensity Calibration
• Observations and Monitors
• Data Reduction

• Appendix

Important Notice

• The continuum mode for science target observation is not offered in open use. The continuum mode is only available for pointing observations.

System Overview

• Nobeyama 45-m Telescope is one of the largest millimetre radio telescopes in the world.
• The 45-m Telescope covers a frequency range of 20 - 116 GHz with several receivers.
• Mirrors in optics part are used for the receiver selection.
• Output signals from a receiver (IF signals) are processed in the IF chains, and fed to backends.
• There are two backends, one is "SAM45" for spectroscopic observations, and the other is "Continuum BE" for continuum observations.

Figure 1: Schematic system block diagram of the Nobeyama 45-m Telescope.

A capability of the Nobeyama 45-m Telescope for this season

Table 1: Summary of the capability of the Nobeyama 45-m Telescope for this season

(*1) Beam squint of H22 respect to H40 is ∼4 arcsec., which is small enough compared to the beam size of H22 (∼72 arcsec.) for most of the observations. (*2) Beam squint of H22 respect to Z40 is ∼2 arcsec. (see acceptance report material for detail), which is small enough compared to the beam size of H22 (∼72 arcsec.) for most of the observations. (*3) For observatiosn of 72 GHz band, FOREST can be used, but the optimal tuning parameters are not searched completely. Typical Tsys are (72 GHz) 300 K, (80 - 110 GHz) 150 K, and (115 GHz) 300 K. (*4) From the limitation of the number of backend (16), two IFs of four have to be choiced.

• Links to each sub-system for detail
  • Antenna
  • Frontend
    • H22
    • H40
    • Z45
    • FOREST
  • Backend
    • SAM45
    • Continuum BE

Location of the Nobeyama 45-m Telescope

• Longitude: E 138^d 28^m 21.2^s
• Latitude: N 35^d 56^m 40.9^s
• Altitude: 1,350 m
• Pinpointing the Nobeyama 45-m Telescope on Google Map

Antenna

Beam Size and Efficiency

Notes: The errors of the efficiencies are mainly due to the uncertainty of brightness temperature of the planets.

(*) Based on the relative measurements between normal and filter modes

• Users are recommended to avoid to observe targets located within 30 degrees from the Sun because the thermal deformation of the antenna degrades the efficiencies.
• Users who would like to observe the Sun or targets near the Sun should take care of them.
• Additional information is available here.

Pointing Accuracy and Strategy

• Typical accuracy of ∼3 arcsec (rms) will be achieved by
  • five-point cross observations of a SiO maser (spectroscopy observations)
    or
  • cross scan observations of planets (continuum observations)
• List of pointing sources:
  • SiO maser: web page, CSV file
  • Continuum: CSV file; Please check the recent flux of source. (e.g., Submillimeter Calibrator List @ SMA)
• It is appropriate to conduct a pointing measurement and correction every 1 - 1.5 hours.
  • It is appropriate to conduct a pointing measurement and correction every 30 minutes during the sunrise and sunset when the outside temperature changes drastically.
• The pointing accuracy above is achievable for wind speed of less than 4 m/s. It can be degraded if wind velocity exceeds 10 m/s.
• Users are recommended to avoid to observing targets located within 30 degrees from the Sun because the thermal deformation of the antenna degrades the pointing accuracy.
• Users who would like to observe the Sun or targets near the Sun should take care of them.
• For the simultaneous observations with H22 and H40 receivers:
  - Pointing measurements should be done with H40 receiver.
  - Please note that the beam squint of H22 respect to H40 is ∼4 arcsec., which is small enough compared to the beam size of H22 (∼72 arcsec.) for most of the observations.

misc.

• Definitions of
  • Az = 0 deg for north, 90 deg for east
  • El = 90 deg for zenith

Frontends

• Frontend Information
  • H22
  • H40
  • Z45
  • FOREST

Backends

SAM45 (Spectral Analysis Machine for the 45-m telescope): for spectroscopic observations

• FX-type correlator
• Process 16 IFs simultaneously
• Input bandwidth: 2 GHz
• Integration time
  • OTF: 0.1 sec or 0.04 sec (dumping time)
  • Position Switch (PoSW): 1.0 sec. x (integer)
  • On-On: 1.0 sec. x (integer)

• References:
  • Kuno, N. et al., "New observing system of the 45-m telescope at Nobeyama Radio Observatory", General Assembly and Scientific Symposium, 2011 XXXth URSI, JP2-19 (2011) https://ieeexplore.ieee.org/document/6051296/?arnumber=6051296
  • Kamazaki, T. et al., "Digital Spectro-Correlator System for the Atacama Compact Array of the Atacama Large Millimeter/submillimeter Array", Publications of the Astronomical Society of Japan 64, 29 (16pp) (2012). [ADS]

Available Settings without Spectral Window (SpW) mode

• For a set of IF01 - 08 (=SAM45 Sub-Array 1):
  • The number of channels of output spectrum is fixed to 4096.
  • Users can select channel separation (or bandwidth).
  • This is independent from IF09 - 16 (=SAM45 Sub-Array 2)
• For a set of IF09 - 16 (=SAM45 Sub-Array 2):
  • The number of channels of output spectrum is fixed to 4096.
  • Users can select channel separation (or bandwidth).
  • This is independent from IF01 - 08 (=SAM45 Sub-Array 1)

Available Settings with Spectral Window (SpW) mode: FOREST (4-Beams) only

• For a set of IF01 - 08 (=SAM45 Sub-Array 1):
  • Users can set two(2) spectral windows within a 2 - 4 GHz.: spw1, spw2.
  • These are independent from IF-B (=SAM45 Sub-Array 2)
• For a set of IF09 - 16 (=SAM45 Sub-Array 2):
  • Users can set two(2) spectral windows within a 2 - 4 GHz.: spw1, spw2.
  • These are independent from IF-A (=SAM45 Sub-Array 1)
• Each spectral window:
  • The number of channels of output spectrum is fixed to 2048.
  • Users can set channel separation (or bandwidth) and position for each spectral window.

• See also
  • Special Notes for Spectral Window Mode of SAM45 with FOREST in Appendix

Continuum BE (for continuum observations)

• Total power detector + 16-bit AD
• Process two(2) IFs simultaneously for a single receiver.
• Process up to three(3) IFs simultaneously only for the H22 and H40 simultaneous observations.

Distribution of IFs to Backends

Spectroscopic observations with SAM45

• Connections between receivers and SAM45 are very complicated.
• Please refer to sample device tables:
  • H22
  • H40
  • Z45
  • H22 & H40 (Simultaneously)
  • H22 & Z45 (Simultaneously)
  • FOREST
    
    • 4-beam Normal (non-SpW)
    • 4-beam Spectral Window Mode (with SpW)
    • 2-beam On-On Mode
    • 1-beam (Single-beam)
• See also Special Notes for Spectral Window Mode of SAM45 with FOREST in Appendix

Continuum observations with Continuum BE

• Connections between receivers and Continuum BE are set manually by assistant/observer.

Observing Modes

Spectroscopic observations with SAM45

Three(3) observing modes, position switching (PoSW), On-The-Fly (OTF) mapping, and ON-ON, are available. Frequency switching is NOT available. Chopping/wobbing of the sub-reflector is NOT available. Beam switching is NOT available for spectroscopic observations.

• Position switching (PoSW) mode:
  • The target position (ON position) and nearby sky position (OFF position) are alternately observed to subtract atmospheric emission.
  • It is suited for relatively deep observations of a single point or a small number of observing points of a small area of the sky.
• On-The-Fly (OTF) mode:
  • Continuous acquisition of the data during a raster scan of the telescope.
  • It is appropriate for wide area mapping of a (relatively) bright line.
• ON-ON mode (FOREST only):
  • The target position (ON position) is always observed either the Beam-1 or 3 (beam separation is ∼70 arcsec), except an antenna slew time.
  • It is suited for deep observations of a single point.
  • The apparent size of target should be smaller than beam size.
  • See Nakajima et al. 2013, PASP, 125, 252 for detail.

Continuum observations with Continuum BE

Beam switching with chopper wheel is always used. Chopping/wobbling of the sub-reflector is NOT available.

• Cross scan

Absolute Intensity Calibration

Spectroscopic observations with SAM45

• Standard Procedure:
  • The observatory provides information on efficiencies.
  • Users are recommended to measure IRR (Image Rejection Ratio): only 2SB receivers
  • Users calibrate their data using the efficiency (all receivers) and the IRR (2SB receivers only).

• Option for Strong Lines:
  • The observatory provides information on standard sources including calibrated intensity (in T_mb scale).
  • Users observe a standard source during their observations.
    • A small mapping observation is recommended in order to reduce the effects of pointing variability.
  • Users calibrate their data using the observed standard source data.

Observations and Monitors

Remote Observation

• Please see Remote Observation
  • from Mitaka Campus, National Astronomical Observatory of Japan
  • from Your Home Institute in Japan
  • from Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) in Taiwan
  • from Korea Astronomy and Space Science Institute (KASI) in Korea

Monitor

• Please see Monitors

Data Reduction

Spectroscopic observations with SAM45

• PoSW, ON-ON: NEWSTAR / Java NEWSTAR
• OTF : NOSTAR

Appendix

Special Notes for Spectral Window Mode of SAM45 with FOREST

• All beams and polarisations of the FOREST should be the same frequency setting.
  • Users should decide ONE(1) frequency for the 1st LO.
• Two(2) groups of IF chains are available: IF-A (IF01 - 08) and IF-B (IF09 - 16).
• Each group (IF-A/IF-B) contains IF outputs from all beams and polarisations, 1-H, 1-V, 2-H, 2-V, 3-H, 3-V, 4-H, and 4-V.
• Users should decide which IF-Sideband (USB-L/USB-H/LSB-L/LSB-H) assigns to IF-A and IF-B, respectively.
• In IF-A (=SAM45 Sub-Array 1):
  • Users can set two(2) spectral windows within a 2 - 4 GHz.: spw1, spw2.
  • These are independent from IF-B (=SAM45 Sub-Array 2)
• In IF-B (=SAM45 Sub-Array 2):
  • Users can set two(2) spectral windows within a 2 - 4 GHz.: spw1, spw2.
  • These are independent from IF-A (=SAM45 Sub-Array 1)
• Each spectral window:
  • The number of channels of output spectrum is fixed to 2048.
  • Users can set channel separation (or bandwidth) and position for each spectral window.

Table 7: Summary of Available Setups of FOREST + SAM45 Spectral Window Mode

Figure 2: Schematic view of an example setting of Spectral Windows.

• Figure 3 shows a schematic view of frequency conversions/setups from FOREST to SAM45 (Spectral Window mode)
• These setups are very complicated.
• Please refer example setups below, initially
• If you have any questions, please contact us via Helpdesk

Figure 3: Schematic view of frequency setups from FOREST to SAM45 (Spectral Window mode)

Example Setups

Example 1) ¹²CO(J=1-0), ¹³CO(J=1-0), C¹⁸O(J=1-0)

Figure 4: Example setup for 12CO, 13CO, and C18O.

Example 2)¹³CO(J=1-0), C¹⁸O(J=1-0), SO, CS(2-1)

Figure 5: Example setup for ¹³CO, C¹⁸O, SO, and CS.

Example 3)¹³CO(J=1-0), C¹⁸O(J=1-0), SO₂, N₂H⁺

Figure 6: Example setup for ¹³CO, C¹⁸O, SO₂, and N₂H⁺.

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