CEDAR email: Arecibo Observatory - 2018 Call for Ionospheric Modification (HF Facility) Proposals

[Eliana Nossa Gonzalez]

Arecibo Call for Ionospheric Modification (HF facility) Proposals
Deadline: Friday, September 28, 2017

Dear Colleagues:

The Arecibo Observatory invites you to submit proposals for the use of the HF facility during 2018.  HF experiments at Arecibo are scheduled by demand in periods of 5-7 days around new moon.  Proposals should specify the associated diagnostics required: the incoherent scatter radar (ISR), active and passive optical instruments and others. Proposals should be submitted via online at http://www.naic.edu/~astro/proposals/hfprop.php before September 28, 2017 (21:00UT).  Information about observing proposals and policies can be found at http://www.naic.edu/~astro/proposals/proposal.shtml

Technical information about our facilities and instrumentation as well as the contacts for specific support are found below. For any further information not addressed in this communication, contact Eliana Nossa (enossa at naic.edu)<mailto:enossa at naic.edu)>


Best regards,





Eliana Nossa



1. Technical information.

1.1.     HF facility.
The HF facility at Arecibo transmits a maximum of 600KW at 5.1MHz, with 22 dB of gain and 13 deg. of half power beam width, or 8.175MHz with almost 26dB and 8.5 deg.  The HF transmission has a Cassegrain design where the primary is the 300 m Arecibo dish, the secondary is a sub-reflector mesh that reflects frequencies lower than 20MHz, and the feed system is composed of an array of three concentric cross dipole antennas at each frequency. The transmitters are connected to the antenna arrays by coaxial lines.  The delay between the generated and the transmitted signal is 3ns. Manual control of the power gain allows ramping up and down the individual antenna power in dB steps. Configurations using CW and pulses as short as few seconds are mostly used.  The system supports linear, O and X modes.
For further information, contact Eliana Nossa (enossa at naic.edu<mailto:enossa at naic.edu>).

1.2. 430 MHz Incoherent Scatter Radar.
The 430 MHz Incoherent Scatter Radar (ISR) is capable of extremely sensitive diagnostics for HF experiments. It can run in parallel with the HF system, being one of the essential tools for diagnostics of the ionosphere modification over Arecibo. Power from the pulsed transmitter (currently about 1.3 to 1.5 MW) can be split with an arbitrary ratio into two beams, allowing sensing through the center of the modified region simultaneously with sensing outside of it or near its edge. Possible geometries are set by the locations of the two feeds on opposite sides of the rotatable azimuth arm, with the minimum zenith angle differences established by the physical sizes of the feeds. Raw data can be collected with a 25 MHz wide data taking system for later analysis while a narrower bandwidth system is used to provide online monitoring. The current coding technique allows 300 m range resolution on the enhanced plasma line while ion line and natural plasma line data are also recorded from the same radar pulses. For further information, contact Michael Sulzer (msulzer at naic.edu<mailto:msulzer at naic.edu>).

1.3. Active optical capability.

The "active" optical instruments (lidars) have the capability to monitor the upper stratosphere to lower thermosphere. The lidar beams are collocated with the ISR volume. We have three systems, two of which are configurable to observe one each of the meteoric metals: Na, Fe, Ca, or Ca+. Alternatively, one of the two metal lidars can be configured as a Rayleigh lidar to measure temperature from the upper stratosphere to the mesosphere, from about 35 to 70 km. The third lidar is a Doppler-resonance lidar that measures temperatures within the metal layer by sensing the Doppler broadening in the D1 resonance line of K.

Request for active optical instrument support for HF experiments must be included in the proposal. We encourage the PIs to contact our staff for particular optical configurations and further information. For lidar observations, contact Shikha Raizada (shikha at naic.edu<mailto:shikha at naic.edu>), Jens Lautenbach (jlautenbach at naic.edu), or Jonathan Friedman (jonathan at naic.edu<mailto:jonathan at naic.edu>).

1.4. Passive optical instrumentation and Arecibo Observatory Remote Optical Facility (AO-ROF).

At Arecibo, we have a variety of airglow instrumentation. Presently, airglow sensing equipment includes an Ebert-Fastie Spectrometer (OH and O2 bands); two Tilting-Filter Photometers (630.0 nm and 555.7 nm); three Fabry-Perot Interferometers (630.00 nm, 557.7 nm and 844.6 nm), and an All-sky Imager system (630.0 nm and 643.4 nm filters).

The AO-ROF is located on Culebra Island (18 18' 18"N; 65 18' 05"W), Puerto Rico, about 96 miles east of the Arecibo Observatory. The optical instruments at ROF can observe the same thermospheric volume over AO sampled by the Incoherent Scatter Radar (ISR). This capability is especially relevant during the HF campaigns. The ROF is designed to host two optical instruments requiring large domes (5-ft diameter) and four optical instruments that require smaller domes (1-ft diameter). Exterior space is also available for the installation of radio receivers or other kinds of instrumentation.
Presently, ROF hosts an all sky imager system (with filters to observe 630.0nm, 643.4nm and 557.7nm airglow emissions) and a High Frequency receiver. From September, 2017, an all sky imager system for OH bands will be available.  Space can be provided for users to deploy instruments temporarily during the HF campaigns.  For further information, contact Pedrina Santos (pterra at naic.edu<mailto:pterra at naic.edu>).

2. Ionospheric Prediction.
For every campaign, the SAS department will be providing the F2 peak parameters prediction to help the users to define the best way to conduct their experiments. These predictions will be accessible on our website at least a month before every campaign. The predictions will provide different scenarios depending on the solar activity, historical ionosonde, and ISR registers. For further information, contact Christiano Brum (cbrum at naic.edu<mailto:cbrum at naic.edu>).



------
Eliana Nossa, Ph.D.
Research Associate
Space and Atmospheric Sciences
Arecibo Observatory

Advanced Technology & Systems Division
SRI International

HC3 BOX 53995, Arecibo PR 00612
(787) 878 2612 ext 219
eliana.nossa at sri.com<mailto:eliana.nossa at sri.com>
enossa at naic.edu<mailto:enossa at naic.edu>

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