Last Update: 1st August 2017

A Manual of Time Estimator


This page is designed to explain the usage of the time estimators for line observations. There are two time estimators: one is for position switching observations, the other is for On-The-Fly observations. Applicants who aim to observe multi-line and/or multi-targets are requested to estimate the observing time for all the lines and targets and append (i.e., copy and paste) the results after the Science and Technical Justification. Note that NRO requests applicants who wish to carry out continuum observations to estimate the observing time by themselves. The estimation procedure is shown in Observing Plan for Continuum Observations.

Links to the Time Estimators

For position switch observations:
Time Estimator for PSW

For On-The-Fly observations:
Time Estimator for OTF

A Manual of Time Estimator for Position Switching Observations

Since the time estimator uses JavaScript, please enable JavaScript. If JavaScript is forbidden in your browser, the message will be printed on "* Messsages:" field.

The meaning of each parameter of Time Estimator for Position Switch (PSW) Observations is explained in this section. If parameters you input are wrong, the error message will pop up.

The time estimator for PSW consists of 10 parameters:

By clicking "Calc" button, the calculation will be performed, and a summary of input parameters and results are shown at the bottom of the page unless the parameter(s) is/are false. The meaning of the results is as follows:

First four items are estimations for Semester A (from December to March).

  • Scan number for one ON-point_sa =
  • The number of scans for one ON-point when the observation will be done in Semester A.
  • Tsys_obs_sa = (K)
  • Expected system temperature at the maximum elevation of the target in Semester A.
  • Total obs. time_sa = (min)
  • The total observing time for Semester A to achieve the required rms noise level in the unit of minutes.
  • Total obs. time_sa = (hr)
  • Same as above but in the unit of hours.

    Following items are estimations for Semester B (from March to May).
  • Scan number for one ON-point_sb =
  • The number of scans for one ON-point in case of the observation in Semester B.
  • Tsys_obs_sb = (K)
  • Expected system temperature at the maximum elevation of the target in Semester B.
  • Total obs. time_sb = (min)
  • Total observing time in Semester B to achiesve the required rms noise level in the unit of minutes.
  • Total obs. time_sb = (hr)
  • Same as above but in the unit of hours.
  • Version =
  • A version of the time estimator.

    Note that
    1. "Total obs. time" includes OFF integration and telescope slewing time, and NOT includes the overheads for pointing and tuning.
    You must multiply the overhead factor of 1.3 to Total obs. time_sa (or Total obs. time_sb) to obtain final total observing time.

    2. Scan number = (Number of Beams) * (Number of Sequences: on-off or on-on is one sequence), NOT includes polarization.
    The resultant "Scan number for one ON-point" is a number of scans to be observed for one beam (polarisation). Therefore, if you intend to obtain two polarisations simultaneously, you need to include two polarisations in one "Device Table" when you make observing scripts.

    Please copy and paste the input parameters and the results on the end of Science and Technical Justifications.
    You can get correct display by enclosing these text with \begin{verbatim*} and \end{verbatim*} in LaTeX file.

    A Manual of Time Estimator for On-The-Fly Observations

    Since the time estimator uses JavaScript, please enable JavaScript. If JavaScript is forbidden in your browser, the message will be printed on "* Messsages:" field.

    The explanation for Time Estimator for OTF Observations is described in this section. For detailed information about On-The-Fly observations, applicants should refer to A Guide to OTF Observations with 45-m. Especially on choosing observing parameters, refer to Determining Parameters and Sensitivities.

    In order to calculate the observing time for OTF, there are 14 parameters to be filled:

    When you click "calc" button, the observing time will be calculated with your input parameters, and a summary of input parameters and results are shown at the bottom of the page. The meaning of the results is as follows:

  • 1.theta [deg] = Not available (Note theta = 0)
  • An initial rotation angle of a rotator. The initial rotation angle set to be 0 for all OTF observations.
  • 2.Beam overlapped area = ["] * ["]
  • The beam overlapped area for observations with FOREST. Since other receivers are all single beam, there is no meaning for these receivers. In the 2017--2018 observing season, the scans of 4 beams must be overlapped due to the limitation of the use of FOREST. Thus, the beam overlapped area is (Length of mapping area along the scans - 50")*(Length of mapping area perpendicular to the scans - 50").
  • 3.vscan is ["/sec] ( per 0.1s sample)
  • A scan speed of the Nobeyama 45-m telescope in case that data dump time is 0.1 second.
    NRO recommends that (scan speed ["/sec]) x (dump time 0.1[sec]) should not be smaller than 1/3--1/4 of the HPBW.
  • 4.Nrow =
  • A number of scans to map.
  • 5.tapp [sec] = , ttran [sec] = , ttranoff [sec] =
  • Time to accerelate the telescope for each scan, to transit the telescope to next scan and transit to OFF-point. tapp and ttran will be used to make observing scripts.
  • 6.tOFF = [sec] -> [sec]
  • An observing time for OFF-point per one sequence.
    tOFF will also be used for making observing scripts.
  • 7.tOH = [sec]
  • An overhead time per one scan row.
  • 8.ttot(ON) [min] =
  • An expected total ON-source time per one observing script.
  • 9.ttot(OBS) [min]/[hour] =
  • An expected total observing time per one observing script.
    ttot(OBS) does not include the overheads for pointing and tuning. You must multiply the overhead factor 1.3 to ttot(OBS) to obtain final total observing time (For FOREST, the overhead factor is 1.4).
  • 10.eta(ON/OBS) =
  • The ON-source efficiency.
    This value is derived by calculating ttot(ON)/ttot(OBS)
  • 11.tcell(ON) [sec] =
  • An ON-source time per one map grid per one observing script.
  • 12.tcell(OFF) [sec] =
  • An OFF-source time per one map grid per one observing script.
  • 13.Tsys_inp [K] =
  • The system temperature input by the user.
  • 14.Tsys_obs_sa[K] =
  • An expected system temperature at the maximum elevation of the target in Semester A.
  • 15.dTa*_sb[K] =
  • An expected noise temperature per one observing script for each map grid in TA* [K] which could be achieved in Semester A.
    For FOREST, this value indicates the noise temperature for the area which four beams overlap. Applicants should use this value to calculate the total observing time.
  • 16.Tsys_obs_sb[K] =
  • An expected system temperature at the maximum elevation of the target in Semester B.
  • 17.dTa*_sb [K] =
  • Same as 15. but for Semester B.
  • 18.Version =
  • A version of the time estimator

    The total observing time for your OTF observation can be calculated using 9. ttot(OBS), 15. dTa*_sa, and 17. dTa*_sb. Assume the rms noise which you are going to achieve is Trms, number of observing script to achieve Trms (N) can be calculated as

    
    		Nsa=(Trms/dTa*sa)2 (for Semester A),
    Nsb=(Trms/dTa*sa)2 (for Semester B).
    Therefore, the total on-source time can be written as
    
    		Nsattot(OBS) (for Semester A),
    Nsbttot(OBS) (for Semester B).
    Finally, multiplying the overhead factor (F), you can get the total observing time Tobs. The overhead factor is 1.3 except for FOREST whose overhead factor is 1.4.
    
    		Tobs sa= FNsattot(OBS) (for Semester A),
    Tobs sb= FNsbttot(OBS) (for Semester B).

    Please copy and paste the input parameters and the results on the end of Science and Technical Justifications. You can get correct display by enclosing these text with \begin{verbatim*} and \end{verbatim*} in LaTeX file.