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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 240718A: Fermi GBM Final Real-time Localization
  2. GRB 240712A: Swift-BAT refined analysis
  3. GRB 240716A: GECAM-B detection of a long burst
  4. SVOM/GRM In-Flight Trigger of GRB 240716A
  5. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
  6. GRB 240713A: 2.2m CAHA optical limit
  7. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  8. GRB 240715A: Swift/UVOT observations of the XRT sources.
  9. GRB 240715A: Swift-XRT observations
  10. GRB240713A: Swift/UVOT Upper LImits
  11. EP240708a: X-ray follow-up observations with Swift/XRT
  12. GRB 240715A: GECAM-C detection of a short burst
  13. Konus-Wind detection of GRB 240715A
  14. LIGO/Virgo/KAGRA S240716b: Updated Sky localization
  15. GRB 240713A: Swift-XRT observations
  16. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  17. GRB 240712A: Swift-XRT refined Analysis
  18. SVOM/GRM In-Flight Trigger of GRB 240715A
  19. GRB 240713A: LAST optical upper limit
  20. LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
  21. GRB 240715A: Swift ToO observations
  22. Fermi GRB 240715A: Global MASTER-Net observations report
  23. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  24. GRB 240715A: Fermi GBM Observation
  25. GRB 240712A ATCA radio observations
  26. GRB240715A: GRANDMA Optical Upper Limits
  27. IPN triangulation of GRB 240715A (short)
  28. GW s240422ed: Swift UVOT follow-up
  29. GRB 240712A: Swift/UVOT Upper Limits
  30. EP-WXT flaring star and the optical flaring activity during its decay phase
  31. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  32. The EP-WXT source triggered on July 14th is likely a flaring star
  33. GRB 240715A: Fermi GBM Final Real-time Localization
  34. GRB 240713A: Tiled Swift observations
  35. GRB 240713A: J-band upper limit from WINTER
  36. GRB 240713A: NOT optical upper limits on three EP/FXT candidates
  37. GRB 240713A: JinShan optical upper limits
  38. GRB 240713A: OHP/T120 optical upper limit
  39. GRB240713A: X-ray follow-up observation with EP-FXT (duplicate submission of GCN 36859)
  40. GRB240713A: X-ray follow-up observation with EP-FXT
  41. GRB 240713B: AstroSat CZTI detection of a long burst
  42. GRB240713A: Optical upper limit with Kinder observations
  43. Fermi Sub-threshold Observation of GRB240713A
  44. GRB240713A: TAROT and GRANDMA Observations of SVOM/ECLAIRs GRB240713A
  45. GRB240713A : The first probable GRB Located on-Board SVOM by ECLAIRs
  46. Fermi Gamma-ray Burst Monitor trigger 742413075/240711744 is not a GRB
  47. EP240708a: GSP optical upper limit
  48. GRB 240712A: Swift detection of a burst
  49. LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
  50. GRB 240711A: Fermi GBM Final Real-time Localization
  51. Fermi trigger No 742405878: Global MASTER-Net observations report
  52. LIGO/Virgo/KAGRA S240627by: Updated Sky localization and EM Bright Classification
  53. Fermi trigger No 742317942: Global MASTER-Net observations report
  54. EP240708a: KAIT optical upper limit
  55. Fermi GRB 240710A: Global MASTER-Net observations report
  56. GRB 240710A: Fermi GBM Final Real-time Localization
  57. EP240708a: NOT optical observations
  58. EP240708a: SVOM/C-GFT optical upper limit
  59. EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
  60. EP240708a: Optical upper limits with Kinder observations
  61. EP240708a: EP-WXT detection of a fast X-ray transient
  62. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  63. EP240703b: GSP optical upper limit
  64. Fermi Gamma-ray Burst Monitor trigger 741911057/240705933 is not a GRB
  65. GRB 240705A: Fermi GBM Final Real-time Localization
  66. EP240703b: TRT optical upper limits
  67. EP240703a: TRT further optical observation
  68. EP240702a: TRT optical upper limits
  69. Konus-Wind detection of GRB 240627A
  70. IPN triangulation of GRB 240628B (short)
  71. LIGO/Virgo/KAGRA S240705at: Updated Sky localization
  72. EP240703a and EP240703b: Swift/XRT upper limits
  73. LIGO/Virgo/KAGRA S240705at: Identification of a GW compact binary merger candidate
  74. EP240703a: KAIT optical upper limit
  75. EP240703a: BTA observations
  76. EP240703c: Kinder optical follow-up and Swift XRT observations
  77. EP240703a: BOOTES-3 optical upper limit
  78. EP240703a: Liverpool Telescope optical follow-up observations
  79. EP240703a/GRB 240703A: TRT optical candidate likely not real
  80. EP240703a: Kinder optical follow-up observations
  81. EP240703c: EP-WXT detection of an X-ray transient
  82. LIGO/Virgo/KAGRA S240703ad: Updated Sky localization
  83. LIGO/Virgo/KAGRA S240703ad: Identification of a GW compact binary merger candidate
  84. EP240703a/GRB 240703A: TRT and JinShan decaying optical afterglow candidate
  85. IPN triangulation of GRB 240627A
  86. GRB 240619A: Host galaxy redshift from VLT/X-shooter
  87. LIGO/Virgo/KAGRA S240422ed: Updated significance estimate
  88. The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT
  89. EP240703b: EP-WXT detection of a fast X-ray transient
  90. Konus-Wind detection of GRB 240703A (a counterpart of EP240703a)
  91. EP240702a: Swift/XRT upper limit
  92. EP240703a: EP-WXT detection of a fast X-ray transient
  93. EP240702a: GSP optical upper limit
  94. The first three GRBs detected by SVOM: GRB 240627B, GRB 240629A and GRB 240702A
  95. GRB 240702A: BALROG localization (Fermi Trigger / GRB 240702885)
  96. Fermi GRB 240702A: Global MASTER-Net observations report
  97. GRB 240702A: Fermi GBM Final Real-time Localization
  98. EP240702a: EP-WXT detection of a fast X-ray transient
  99. LIGO/Virgo/KAGRA S240627by: Upper limits from Swift/BAT-GUANO
  100. Fermi Gamma-ray Burst Monitor trigger 741448122/240630575 is not a GRB

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