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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').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. GRB 240418A: NOT optical upper limits
  2. GRB 240418A: Enhanced Swift-XRT position
  3. GRB 240418A: AKO Upper Limit
  4. GRB 240411A: GOTO early optical upper limits
  5. Swift GRB240418.85: Global MASTER-Net observations report
  6. GRB 240418A: Swift detection of a burst
  7. EP240417a: EP-WXT detection of a fast X-ray transient
  8. Fermi GRB 240417A: Global MASTER-Net observations report
  9. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  10. EP240416A: Terskol Zeiss-2000 optical upper limit
  11. EP240416A: Khureltogoot optical upper limit
  12. Improved IPN triangulation of GRB 240411A
  13. EP240416a: BOOTES-2/TELMA Optical Upper Limit
  14. EP240414a: GSP detects optical candidate counterpart AT2024gsa
  15. LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
  16. IceCube-Cascade 240416A: Upper limits from a search for additional neutrino events in IceCube
  17. GRB 240417A: Fermi GBM Final Real-time Localization
  18. EP240414a: Pan-STARRS detects re-brightening of the candidate counterpart AT2024gsa
  19. LIGO/Virgo/KAGRA S240413p: historical ATLAS and ZTF observations of the candidate AGN counterpart
  20. GRB 240415A: Glowbug gamma-ray detection
  21. GRB 240414A: Glowbug gamma-ray detection
  22. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  23. GRB 240415B: GECAM-B detection
  24. EP 240416a: Xinglong and NOT decaying optical counterpart
  25. GRB 240415A: Swift-BAT refined analysis
  26. EP240416A: MASTER optical observations
  27. GRB 240411A: Glowbug gamma-ray detection
  28. GRB 240414A: Swift-BAT refined analysis
  29. EP240416a: Kinder optical counterpart candidate
  30. EP240416a: EP-WXT detection of a fast X-ray transient
  31. GRB 240414A: AbAO optical upprer limit
  32. GRB 240415A: Swift/UVOT Detection
  33. EP240413a: BOOTES-2/TELMA Optical Upper Limit
  34. GRB 240415A: Fermi GBM Observation
  35. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  36. GRB 240415A: Earliest optical followup with the Kinder observations
  37. GRB 240414A: GMG observation
  38. EP 240414a: BOOTES-4/MET Optical Upper Limits
  39. EP240414a: EP-FXT follow-up observation
  40. GRB 240415A: Enhanced Swift-XRT position
  41. GRB 240415B: Swift ToO observations
  42. GRB 240415B: Swift/BAT-GUANO Correction
  43. GRB 240415B: Swift/BAT-GUANO arcminute localization of a short burst
  44. GRB 240415A: OHP/T193 optical observations
  45. GRB 240415A: optical afterglow detection from the INAF Asiago Observatory
  46. GRB 240415A: SAO RAS optical observations
  47. GRB 240415A: Mondy optical transient detection (photometry correction in GCN 36118 )
  48. GRB 240414A: Fermi GBM Observation
  49. Fermi GRB 240415A: Global MASTER-Net observations report
  50. GRB 240415A: Mondy optical transient detection
  51. GRB 240414A: Photometric observation from 2.2m CAHA
  52. IceCube-240412A: Upper limits from a search for additional neutrino events in IceCube
  53. GRB 240414A: Swift/UVOT Detection
  54. LXT 240402A/GRB 240402B: Swift follow-up observations
  55. GRB 240414A: Mondy optical observations
  56. GRB 240414B: Fermi GBM Final Real-time Localization
  57. GRB 240414A: AKO Optical Upper Limit
  58. X-ray transient EP 240414a - GTC spectroscopic observations
  59. GRB 240415A: Prompt Swift-XRT observations
  60. GRB 240415A: Swift detection of a burst
  61. GRB 240415A: Fermi GBM Final Real-time Localization
  62. EP240413a: Upper limits from GECAM-B Observation
  63. EP 240414a: NOT optical counterpart confirmation
  64. GRB 240414A: Swift-XRT refined Analysis
  65. GRB240414A : J-band upper limits from WINTER
  66. GRB 240414A: Enhanced Swift-XRT position
  67. GRB 240414A : OHP/T193 second epoch of optical follow-up and afterglow detection
  68. GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  69. LIGO/Virgo/KAGRA S240413p: No Counterparts in DDOTI/OAN Optical Observations
  70. EP240413A: GOTO optical upper limits
  71. GRB 240414A: Skynet Optical Afterglow Observations
  72. Fermi trigger No 734754044: Global MASTER-Net observations report
  73. Swift GRB 240414A: Global MASTER-Net observations report
  74. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  75. IPN triangulation of GRB 240410A
  76. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  77. EP240414a: EP-WXT detection of a fast X-ray transient
  78. IPN triangulation of GRB 240411A
  79. Fermi-LAT gamma-ray observations of IceCube-240412A
  80. GRB 240414A : MITSuME Akeno optical upper limits
  81. GRB 240414A: Redshift confirmation from GTC/OSIRIS+
  82. EP240413a: EP-WXT detection of a fast X-ray transient
  83. GRB 240414A : OHP/T193 redshift determination
  84. GRB 240414A : OHP/T193 optical counterpart detection
  85. GRB 240414A: Swift detection of a burst
  86. LIGO/Virgo/KAGRA S240413p: Updated Sky localization
  87. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  88. LIGO/Virgo/KAGRA S240413p: Zwicky Transient Facility observations
  89. EP240408a: GSP optical upper limit
  90. GRB 240411B: CrAO/ZTSh optical observations
  91. GRB 240411B: Kinder observations with Lulin observatory
  92. LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
  93. LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
  94. GRB 240411B: HiPERCAM/GTC observation
  95. IceCube Alert 240412.23: Global MASTER-Net observations report
  96. GRB 240411B: Swift-BAT refined analysis
  97. GRB 240411B: Swift-XRT refined Analysis
  98. IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
  99. GRB 240411B: 1.3m DFOT Optical observations
  100. GRB 240411A: GRBAlpha detection

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