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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"

32509 results found.

  1. EP240416a: BOOTES-2/TELMA Optical Upper Limit
  2. EP240414a: GSP detects optical candidate counterpart AT2024gsa
  3. LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
  4. EP240414a: Pan-STARRS detects re-brightening of the candidate counterpart AT2024gsa
  5. LIGO/Virgo/KAGRA S240413p: historical ATLAS and ZTF observations of the candidate AGN counterpart
  6. GRB 240415A: Glowbug gamma-ray detection
  7. GRB 240414A: Glowbug gamma-ray detection
  8. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  9. GRB 240415B: GECAM-B detection
  10. EP 240416a: Xinglong and NOT decaying optical counterpart
  11. GRB 240415A: Swift-BAT refined analysis
  12. EP240416A: MASTER optical observations
  13. GRB 240411A: Glowbug gamma-ray detection
  14. GRB 240414A: Swift-BAT refined analysis
  15. EP240416a: Kinder optical counterpart candidate
  16. GRB 240414A: AbAO optical upprer limit
  17. GRB 240415A: Swift/UVOT Detection
  18. EP240413a: BOOTES-2/TELMA Optical Upper Limit
  19. GRB 240415A: Fermi GBM Observation
  20. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  21. GRB 240415A: Earliest optical followup with the Kinder observations
  22. GRB 240414A: GMG observation
  23. EP240414a: EP-FXT follow-up observation
  24. GRB 240415B: Swift ToO observations
  25. GRB 240415A: OHP/T193 optical observations
  26. GRB 240415A: optical afterglow detection from the INAF Asiago Observatory
  27. GRB 240415A: SAO RAS optical observations
  28. GRB 240415A: Mondy optical transient detection (photometry correction in GCN 36118 )
  29. GRB 240414A: Fermi GBM Observation
  30. Fermi GRB 240415A: Global MASTER-Net observations report
  31. GRB 240415A: Mondy optical transient detection
  32. GRB 240414A: Photometric observation from 2.2m CAHA
  33. IceCube-240412A: Upper limits from a search for additional neutrino events in IceCube
  34. GRB 240414A: Swift/UVOT Detection
  35. LXT 240402A/GRB 240402B: Swift follow-up observations
  36. GRB 240414A: Mondy optical observations
  37. GRB 240414A: AKO Optical Upper Limit
  38. X-ray transient EP 240414a - GTC spectroscopic observations
  39. GRB 240415A: Prompt Swift-XRT observations
  40. GRB 240415A: Swift detection of a burst
  41. EP240413a: Upper limits from GECAM-B Observation
  42. EP 240414a: NOT optical counterpart confirmation
  43. GRB240414A : J-band upper limits from WINTER
  44. GRB 240414A : OHP/T193 second epoch of optical follow-up and afterglow detection
  45. GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  46. LIGO/Virgo/KAGRA S240413p: No Counterparts in DDOTI/OAN Optical Observations
  47. EP240413A: GOTO optical upper limits
  48. GRB 240414A: Skynet Optical Afterglow Observations
  49. Swift GRB 240414A: Global MASTER-Net observations report
  50. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  51. IPN triangulation of GRB 240410A
  52. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  53. IPN triangulation of GRB 240411A
  54. Fermi-LAT gamma-ray observations of IceCube-240412A
  55. GRB 240414A : MITSuME Akeno optical upper limits
  56. GRB 240414A: Redshift confirmation from GTC/OSIRIS+
  57. GRB 240414A : OHP/T193 redshift determination
  58. GRB 240414A : OHP/T193 optical counterpart detection
  59. LIGO/Virgo/KAGRA S240413p: Updated Sky localization
  60. LIGO/Virgo/KAGRA S240413p: Zwicky Transient Facility observations
  61. EP240408a: GSP optical upper limit
  62. GRB 240411B: CrAO/ZTSh optical observations
  63. GRB 240411B: Kinder observations with Lulin observatory
  64. LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
  65. LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
  66. GRB 240411B: HiPERCAM/GTC observation
  67. GRB 240411B: Swift-BAT refined analysis
  68. GRB 240411B: 1.3m DFOT Optical observations
  69. GRB 240411A: GRBAlpha detection
  70. GRB 240411B: OHP/T193 optical observations
  71. GRB 240405A: Glowbug gamma-ray detection
  72. GRB 240411B: LCO optical afterglow detection
  73. GRB 240408B: GRBAlpha detection
  74. EP240408A: MASTER optical observations
  75. EP240408a: GROND detection of a candidate counterpart
  76. EP240408a: Swift follow-up observation
  77. X-ray transient EP240315a: second epoch e-MERLIN radio observations
  78. GRB 240405A: GRBAlpha detection
  79. IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
  80. Fermi GRB 240408A: Global MASTER-Net observations report
  81. GRB 240402C: CALET Gamma-Ray Burst Monitor detection
  82. Fermi GRB 240407A: Global MASTER-Net observations report
  83. Fermi-LAT gamma-ray observations of IceCube-240327B
  84. Fermi-LAT gamma-ray observations of IceCube-240327A
  85. LXT 240402A/GRB 240402B: rest-frame energetics from Konus-Wind observation
  86. Fermi GRB 240405B: Global MASTER-Net observations report
  87. GRB 240402C: Glowbug gamma-ray detection
  88. GRB 240331A: GRBAlpha detection
  89. LXT 240402A/GRB 240402B: GECAM-C refined analysis
  90. Swift satellite resumes pointed science observations
  91. GRB 240403A: Glowbug gamma-ray detection
  92. LXT 240402A/GRB 240402B: Glowbug gamma-ray detection
  93. X-ray transient LXT 240402A: WFST optical upper limits​
  94. Konus-Wind detection of LXT 240402A/GRB 240402B
  95. GRB/FXT 240402B: Kinder optical counterpart candidate
  96. IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
  97. GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
  98. X-ray transient LXT240402A: AST3-3 optical upper limits
  99. LXT 240402A: EP-FXT detection of the X-ray afterglow
  100. Fermi GRB 240404A: Global MASTER-Net observations report

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