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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').

2445 results found.

  1. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  2. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfr and AT2024hfs
  3. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  4. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  5. GRB 240502C: GOTO possible optical counterpart candidates
  6. LIGO/Virgo/KAGRA S240422ed: Host redshifts of AT2024hfq, AT2024hfu, and AT2024hmo from DBSP
  7. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  8. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  9. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  10. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  11. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  12. EP240426a: YAHPT optical upper limit
  13. LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
  14. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  15. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  16. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  17. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  18. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  19. S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
  20. LIGO/Virgo/KAGRA S240422ed: Magellan Spectrum of GW-MMADS Candidate AT2024hdo Indicates a Type II SN
  21. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  22. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  23. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  24. LIGO/Virgo/KAGRA S240422ed: MOSFIRE spectroscopy of the DECam GW-MMADS candidate AT 2024hdn
  25. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  26. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  27. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  28. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  29. GRB 240419A: Possible ATCA radio detection
  30. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  31. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  32. GRB240418A - Candidate afterglow from NIRES
  33. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  34. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  35. EP240417a: YAHPT Optical Upper Limits
  36. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  37. EP240416a: Kinder optical counterpart candidate
  38. GRB 240415A: Mondy optical transient detection
  39. LXT 240402A/GRB 240402B: Swift follow-up observations
  40. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  41. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  42. GRB 240414A: Swift detection of a burst
  43. IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
  44. EP240408a: Swift follow-up observation
  45. X-ray transient EP240331a: Kinder optical upper limits
  46. IceCube-240327B - IceCube observation of a high-energy neutrino candidate track-like event
  47. IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
  48. X-ray transient EP240315a: e-MERLIN radio observations
  49. Transient EPW20240219aa: REM optical/NIR further observations
  50. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  51. GRB 240315C / X-ray transient EP240315a: Swift/BAT detection
  52. Swift satellite in safe mode
  53. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  54. X-ray transient EP240315a: orphan FXT?
  55. X-ray transient EP240315a: Kinder follow-up observations for AT 2024eju with Lulin observatory
  56. AT2024eju: followup observations with Liverpool Telescope suggest a fading transient
  57. X-ray transient EP240315a: ATLAS detection of a possible optical counterpart AT2024eju
  58. IceCube-240307A - IceCube observation of a high-energy neutrino candidate track-like event
  59. IceCube-240229A - IceCube observation of a high-energy neutrino candidate track-like event
  60. Transient EPW20240219aa: upper limit in gamma-ray range from SPI-ACS/INTEGRAL observations
  61. Transient EPW20240219aa: Liverpool Telescope non-detection and limiting magnitude
  62. Fermi GBM Sub-Threshold Detection of EPW20240219aa as a likely GRB
  63. GRB 240209A: Classification of AT2024cew/GOTO24pw as Type Ia-pec supernova
  64. GRB 240214A/1H 0451-560: MAXI/GSC detection
  65. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  66. IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
  67. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  68. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  69. IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
  70. GRB 240101B: Swift-BAT refined analysis
  71. IceCube-231211A - IceCube observation of a high-energy neutrino candidate track-like event
  72. IceCube-231202A - IceCube observation of a high-energy neutrino candidate track-like event
  73. IceCube-231125A - IceCube observation of a high-energy neutrino candidate track-like event
  74. GRB 231117A: Keck spectroscopy of afterglow candidate
  75. MAGIC observation of GRB 231115A, a possible magnetar giant flare
  76. GRB231115A: Liverpool Telescope imaging
  77. GRB 231115A: AGILE/MCAL upper limits
  78. GRB 231115A: significance of INTEGRAL localization alignment with M82
  79. GRB 231111A: TNG tentative redshift
  80. GRB231110A: WFST Observation and upper limits
  81. IceCube-231103A - IceCube observation of a high-energy neutrino candidate track-like event
  82. IceCube-231027A - IceCube observation of a high-energy neutrino candidate track-like event
  83. IC231004A: GRANDMA observations of AT2023uqf/ZTF23abidzvf candidate
  84. GRB 231017A: Mondy optical observations. A possible candidate for an afterglow or host galaxy.
  85. GRB 230911C: ATCA detection of possible radio counterpart
  86. IC231004A: Classification of AT2023uqf/ZTF23abidzvf as a rapidly-evolving supernova with CSM interaction
  87. IceCube-231014A - IceCube observation of a high-energy neutrino candidate track-like event
  88. IceCube-231004A - IceCube observation of a high-energy neutrino candidate track-like event
  89. transient AT2023sva: A Binary Driven Hypernova with a possible associated supernova
  90. LIGO/Virgo/KAGRA S230904n: Classification of the candidate AT2023rkw with DBSP
  91. Correction to Fermi GBM Statement for Trigger 716527670/230916144
  92. LIGO/Virgo S230917af: Swift XRT observations, 6 X-ray sources
  93. IceCube-230914A - IceCube observation of a high-energy neutrino candidate track-like event
  94. GRB 230911D: NuSTAR Detection of Prompt Emission
  95. IceCube-230823A - IceCube observation of a high-energy neutrino candidate track-like event
  96. GRB 230812B: Assy optical observations, possible SN rise
  97. GRB 230812B: SAO RAS observations, possible re-brightening
  98. GRB 230812B: SAO RAS optical observations
  99. GRB230816A: Possible host and GIT detection of optical counterpart
  100. GOTO confirmation and possible host galaxy of GRB230812B optical afterglow

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