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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"

24822 results found.

  1. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  2. EP250101a: Liverpool Telescope optical upper limit
  3. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  4. GRB 250101a: Liverpool Telescope optical follow-up
  5. GRB 250103B: Swift detection of a burst
  6. GRB 250103A: Xinglong 2.16m Optical Candidate
  7. GRB 250101B: SVOM/GRM observation
  8. GRB 250103A: GOTO optical upper limit
  9. GRB 250103A: SVOM/C-GFT optical upper limit
  10. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  11. EP241231b: optical upper limit with the Liverpool Telescope
  12. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  13. GRB 250103A: SVOM detection of a long burst
  14. EP250101a: Xinglong optical upper limit
  15. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  16. GRB 250101A: Swift-BAT refined analysis
  17. GRB 250101A: further SAO RAS optical observations
  18. GRB 250101A: LCO optical counterpart detection
  19. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  20. GRB 250101A: Swift/UVOT Detection
  21. GRB 250101A: 1.6m Mephisto multi-band optical followup
  22. GRB 250101A: Swift-XRT refined Analysis
  23. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  24. GRB 250101A: LCOGT optical afterglow detection
  25. GRB 250101A: OASDG optical observations
  26. GRB 250101B: Fermi GBM Final Real-time Localization
  27. GRB 250101A: SAO RAS observations of optical brightening
  28. GRB 250101A: BOOTES-4/MET optical afterglow detection
  29. GRB 250101A: AKO Optical Afterglow Detection
  30. GRB 250101A: SAO RAS optical observations
  31. GRB 250101A: Enhanced Swift-XRT position
  32. LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
  33. GRB 250101A: SVOM/C-GFT early optical observations
  34. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  35. GRB 250101A: Nanshan/HMT optical observations
  36. GRB 250101A : GIT optical detection
  37. GRB 250101A: GMG Optical Observation
  38. GRB 250101A: Swift detection of a burst with an optical counterpart
  39. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  40. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  41. GRB 241229B: Continued CrAO ZTSh observations
  42. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  43. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
  44. LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
  45. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  46. LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
  47. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  48. GRB 241229B: SVOM/GRM observation
  49. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  50. EP241217A: J band upper limit by SYSU 80cm telescope
  51. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  52. GRB 241229B: SAO RAS optical upper limit
  53. GRB 241228B: SAO RAS optical observations
  54. GRB 241229A: SAO RAS optical observations
  55. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  56. GRB 241229A: Swift-XRT observations
  57. EP240702a: 7DT Optical upper limits
  58. GRB 240606B: 7DT Optical upper limits
  59. LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate
  60. GRB 241229B: Swift-BAT refined analysis
  61. LIGO/Virgo/KAGRA S241225v: Updated Sky localization
  62. LIGO/Virgo/KAGRA S241225c: Updated Sky localization and EM Bright Classification
  63. GRB241229B: UVOT upper limits
  64. GRB 241228B: Fermi GBM Observation
  65. GRB 241228B: Swift-XRT afterglow detection
  66. GRB 241229B: Fermi GBM Observation
  67. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  68. GRB 241228A: Mondy optical afterglow observations
  69. GRB 241229A: GOTO optical upper limits
  70. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  71. GRB 241228A: NOT optical upper limits
  72. GRB 241228B: LCO optical observation
  73. GRB 241228A: Swift-BAT refined analysis
  74. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  75. GRB 241228A: Fermi GBM Observation
  76. GRB241228B: GROWTH-India Telescope optical observations
  77. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  78. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  79. GRB 241228A: GROWTH-India telescope optical upper limit
  80. GRB 241228B: TRT optical counterpart confirmation
  81. GRB 241228A: Swift-XRT refined Analysis
  82. GRB 241228A: Swift/UVOT Upper Limits
  83. GRB 241228A: Enhanced Swift-XRT position
  84. GRB 241228A: Swift detection of a burst
  85. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  86. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  87. GRB 241212A: VZLUSAT-2 detection
  88. EP241223a: Mondy AZT-33IK optical observations
  89. GRB 241029A: LCO optical observation
  90. GRB 241223A: Swift-XRT observations
  91. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  92. GRB 241029A: AbAO AS-32 optical observations
  93. GRB 241223A: Fermi GBM Detection
  94. Fermi trigger No 756678579: Global MASTER-Net observations report
  95. LIGO/Virgo/KAGRA S241225c: Identification of a GW compact binary merger candidate
  96. EP241223a
  97. EP241223a: EP-WXT detection of a fast X-ray transient
  98. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  99. GRB241113A: 7DT Optical upper limits
  100. GRB 241223A: GOTO optical observations summary

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