This is where one's creative imagination can really let rip - it is possible to read a chart many ways, and it has to be admitted that as we come to the detail of the story, the charts happily comply with our needs! So let's have some fun!
If I were to choose one chart for Sedna, it would be the chart for the last of the three photographs showing its presence, because that was the point at which the equipment reported a moving body. But it might be interesting to see how the chart of each photograph might reflect the different stages of the goddess Sedna's legend, having a different Ascendant and the planets in different Houses.

The place from which the photographs were taken was near San Diego, California, and the House system used for the following charts is Campanus, a system showing the more spiritual and psychological meanings, rather than down to earth practical as with for instance the Placidus Houses.

Photograph # 1 - taken at UT 6:32.

At first Sedna is content living with her father. Reading the base of the chart as the father's place, Pluto (Scorpio's ruler) represents the father himself, and here it conjuncts Venus, the romantic (5th House) feminine. Sedna is able to focus on herself because she assumes the authority of her father as Saturn in Cancer in 12th House. Neptune on the Descendant sextiling Venus in 5th House all suggests a romantic vision of future partner, absent in fact because the Decendant ruler, Uranus, is firmly in 7th House of partnership. The male principle, Mars, is held poised by trining Saturn who is waiting in the background (12th House) for the right karmic moment to release the catalysing situation that will help Sedna to grow up (opposing Chiron in the 6th House).
Sedna has Leo rising at this point in the story, showing her concern with herself and her appearance. Ruled by the Sun in the 4th House, she is supported in being able to focus on herself by being in her original home with family. The aim however is to be seen, Moon's North Node in 10th House.
Aquarius is on the Descendant, showing the future partner to be Uranus. Uranus is indeed in 7th House of partnership but squares Sun and Mercury, showing difficulties of surprise, sudden changes, and separations, yet to come.

Photograph # 2 - taken at UT 8:03

In the second chart Uranus is on the Descendant showing the sudden arrival of the partner and the marriage which separates Sedna from her romantic dream of partner, a loss that is necessary if there is to be growth. Every individual needs to discover their own autonomy, their own space, if they are to relate in a growthful way. Uranus has only squares to Sun/South Node and Mercury, so it could feel wrong to Sedna even though it is a necessary step.
In this chart Venus/Pluto are now in the 4th House, showing the feminine struggling with early life issues, not yet recognising or accepting that the male principle is partner (Venus squaring Mars in 7th House) still calling on father to put things right (Mercury in 4th House is still communicating mostly with father). Neptune now rules the Descendent and is in 6th House, reflecting the fact of Sedna's marriage being arranged for her.
In both of these first two charts the Midheaven is in Taurus showing that practical consideration of physical survival and security are top of the priority list. However, the Moon's North Node is now in 9th House showing her journey to a different land to live with her husband, and her inner journey realising that physical security is not all that matters.
Virgo has begun to rise, showing how Sedna has begun to establish a sense of her own identity and need for boundaries.

Photograph # 3 - taken at UT 9:38

In the third chart, the Midheaven ideal now is Gemini, to be in communication, and the 3rd House (of communication) is emphasised through containing Sun/South Node, Mercury and Venus. In her distress, Sedna calls to her father and he hears and comes to rescue her. The father (ruler of 4th House) is Jupiter in 12th House unable to act, but sextiling Saturn in 10th House wanting to control the situation. He came to the rescue only to be transformed into the destroyer (Pluto on the base of the chart squaring Mars and Jupiter) as he drives her into the freezing sea. Sedna's relationship with her father is transformed

That Sedna's father tries to get rid of her out of the boat, even after rescuing her from the raven, could be seen as part of that Jupiter-inspired vacillation. The fact is that Sedna cannot go back to the security of her childhood home. She has to give up the original father/daughter relationship, just as women need to pull back the authority they give 'man as father,' before they can relate to 'man as partner.' Sedna becomes herself at last, owning her own power as she sinks into her own territory, at home in the sea of human emotion. In the end of this version of the Sedna myth, the problem we are left with is that Sedna is angry. Other versions may have other endings!

Conclusions - What Sedna may be showing us to do.

I favour using the third photograph as our awakening to Sedna's presence in the sky, the awakening of the feminine to its intrinsic power. Pluto, although conjunct the 3rd House Venus, is itself on the IC of this chart, suggesting that the message of Sedna's story for us now is the importance of transforming the way we relate with each other through speech. There is a transformation in any relationship when we focus on the care we can give, rather than trying to get what we what. What makes that work for us, rather than becoming slaves to the other, is a sense of our own self as valuable in the scheme of things. Knowing our own boundaries and respecting them ourselves, we become able to give to others what they really need in a way that heals. Mars in this chart is the healer (sextiling Chiron).

Getting squared planets to work more positively together can only be done through communicating their different perspectives to each other, and finding the work that involves them all. Mars in Pisces and Venus in Sagittarius are both interested in living in oneness. Mars in Pisces doesn't feel the need to understand or talk about that, but this chart is showing that talking is necessary if the masculine and feminine are not to remain in conflict. The quincunxes and sextiles show another way for squaring planets to connect with each other, through service. In this chart, it is the feminine that reaches out to understand for the sake of the relationship. The masculine needs to listen and accept, and admit to its sensitivity, for the sake of the relationship. This needs to be done internally, within each one of us. Self-talking the problems and listening sensitively to ourselves explaining, we become able to find the healing that we need. This will make it easier to sort out difficulties in relating with everyone, and everything, else.

The spiritual purpose, Taurus North Node on the cusp of 9th House, is perhaps to learn from our experiences with the Earth - learning to live an ecologically balanced lifestyle. Taurus' ruler, the Sagittarian Venus is teaching us that we need to enter into the relationship with Earth by first appreciating what we receive, and then by giving love and caring for her - this would indeed be a transformed relationship following the arrogant devastation humanity has wreaked on Earth up to now. The Moon's North Node in 9th House tells us that it's the intention that counts - so let's aim to go in that direction!

P.S.
This is my offering. There is much more, and different, to be said about Sedna. Let this be part of a conversation where we grow in our understanding of what change in human consciousness is reflected by the discovery of this object in our solar system.